I first meet SuRie at BBC Broadcasting House, a week before she flies out to Lisbon. As a relatively small independent artist, the 29-year-old was thrown in at the deep end when she was selected to represent the United Kingdom at Eurovision back in February, catapulted into the public eye and immediately coloured by our preconceptions of a singing competition that has seen the UK previously present such musical luminaries as "Jemini" and airplane-themed four-piece Scooch.

SuRie is in surprisingly high spirits as we make small talk, given the fact she was up at the crack of dawn to join Holly and Phil on the This Morning sofas, and that – as is tradition when it comes to the UK's Eurovision entry – we both know she has no chance of winning on the big night.

"It has been a whirlwind, but I'm enjoying it," SuRie tells me. "As soon as I knew I'd been selected I immediately wanted to tweak the track. I wanted to record real strings and real piano, and make a few changes to the vocals." A music video had to be shot, followed by a promotional tour across Europe. "They call them parties, but they are gigs," says SuRie. "The one in Tel Aviv was for 30,000 people. Then it's into rehearsals."

SuRie at BBC Broadcasting House

After two years working with other Eurovision entrants (once as a backing singer, the following as musical director), SuRie – real name, Susanna Marie Cork – knows how hectic it'll be once she steps off the plane in Lisbon. But I don't, and I want to understand both what it takes to be a Eurovision competitor and why anyone from the UK would wish to take on the challenge, destined – as they are – to fail, and likely to go down in Wikipedia history as "best known for competing in Eurovision".

As a teenager in Bishop's Stortford, Hertfordshire, SuRie threw herself into every creative activity she could find. There was the cover band she fronted, the jazz ensemble and the orchestra. But after leaving school post A-Levels, years of work on her first album resulted in a product that, in her own words, just wasn't strong enough. Instead of auditioning for the X-Factor or throwing in the towel, she decided to go back to school.

SuRie and the author

It was then, after completing a post-graduate year at the Royal Academy of Music, that SuRie found herself a little lost. "My life was going through all sorts of changes," she says. "I was having a quarter-life crisis. I was trying to find my way, as a jobbing musician, which is tough." And then she found Eurovision. Or Eurovision, to be more precise, found her. "The musical director of Belgium's 2015 entry also studied at the Royal Academy of Music," she explains. "He was hiring singers to support their artist, and I was recommended for the gig."

"I guiltily admit that I'd never watched a Eurovision Song Contest until that point," she continues, eliciting a smile from the BBC publicist now sitting with us. "I hadn't avoided it, it just hadn't been on my radar. I very quickly got the idea that, in fact, Eurovision is a big deal, especially in mainland Europe and further afield. A lot of time, energy, creativity and finance goes into it."

In her first year involved, the Belgian entry came in fourth, and SuRie felt triumphant.

"That night, the intensity and energy from the crowd gave me so much fire in my belly. It reminded me where I need to be, what I do and why I do it. It gave me my life back. I owe so much to Eurovision," she adds. "I mean that."

There's a lot going on as I approach the Altice Arena in Lisbon. It's Thursday morning, days before the final, but thousands of staff, fans, volunteers and journalists are already darting about. People without accreditation are loitering around in the hope of nabbing an autograph.

To the uninitiated, Eurovision starts and ends with the Saturday night frivolities: a jubilant flag-waving parade followed by 20-something performances. The evening is rounded off with some faffing, and as a tipsy British audiences tips over into trashed, the scores come trickling in.

In actual fact, by the time Eurovision hits our screens the show has already been performed in full three times. For those who had to compete in the semi-finals (every country but France, Germany, Italy, the UK, Spain and the host nation, all of whom are guaranteed entry), the final is at least the eighth time they'll have performed their set onstage. Following a blue carpet event on the preceding Sunday, the 1,400 journalists in attendance have been desperately vying for the artists' time. There are receptions in ambassadors' residences; promo events and photo calls from morning until night.

Just a week ago, when I last met up with SuRie, she'd said her goodbyes and sauntered off down the street alone in London – no team in tow, no crazed fans or security detail following her. Here, she's the centre of attention: a permanent police escort, her people on hand at all times.

"Eurovision is a weird one – it's not a catapult, it's actually a boomerang," she says, during a 15-minute catch-up before she has to go and practice waving a flag. "It throws you straight in, then pulls you back out again as soon as it's over. It's important to remember that this isn't reality."

SuRie says she is grateful for the fans who greet her off the bus each day, wanting selfies and signatures. "Their smiling faces at my presence is lovely, even odd. But I know it's not reality."

Looking out at the Portuguese coastline together, we chat about how there has arguably never been a worse time to be Britain's Eurovision entry, what with Brexit and rising tensions with Russia, on top of years of anti-European immigration rhetoric. SuRie has been in Lisbon for nearly a week now, so I ask whether she feels the political climate might impact her chances.

"I haven't seen evidence of that," she replies, "but that’s maybe because I’m not in a realistic bubble. I hope for one night of the year that a song speaks to someone, that their political agendas or other people's political agendas don't overshadow some heart and soul."

Politics aside, it's hardly like Britain regularly does well; we last came top over 20 years ago. But, as SuRie reminds me before she's whisked off in a golf buggy, this is a singing contest after all.

It was something of a revelation, the first time I realised people actually take Eurovision seriously; that it was more than an elaborate excuse to get pissed, masquerading as a camp, trashy singing competition. From the traditionally sarcastic commentary of Terry Wogan (and now Graham Norton), to the UK's consistently dodgy song choices, I’d always seen it as something of a joke. But what becomes increasingly obvious, after just 24 hours on site, is that to much of mainland Europe this is incredibly important, like the World Cup or the Olympics, but with songs and sparkles replacing the sport.

With the scale of Eurovision now dawning on me, I arrange to talk with Noel Curran, the Director General of the European Broadcasting Union (EBU). The driving force behind Eurovision, the EBU is an alliance of public service media organisations based in Switzerland, and has run the competition since its inception in 1956. Having taken up his position last September, this is Noel’s first year in charge, but already he knows you have to look away from the stage to get a real sense of Eurovision's magic.

Noel Curran

"It's a huge event for us, and so well-known across Europe – whatever people's views on it are," he says. "The audience figures are astounding: it'll be watched by around 180 million people."

"Just watch on Saturday night – have a look at how the performers interact with each other," Noel continues. "When a song does well, turn around and see what the competitors in the green room are doing. The fact that countries which are literally at war will be singing in the same audience with delegations in the same room is a statement in and of itself."

Why, then, are Brits so disinterested? "You have to remember that, despite what people in the UK say, seven or eight million people will tune in on Saturday night," says Noel. "That's a lot of people for a linear TV show. People say to me, 'Brits hate Eurovision,' but I don’t get that. It's love-hate. People love to hate it, and they hate to love it."

Benny Royston

A few hours later, I track down Benny Royston. It's not entirely clear to me what it takes to be a Eurovision expert, but by all accounts he is one, so I decide to pick his brains after finding his details online. With Noel's positivity still fresh in my mind, I'm keen to understand what Bristol-based Benny makes of Britain's blasé attitude to the competition as someone who approaches it, like so many others, with such passion and dedication.

Benny believes one reason Brits love to mock Eurovision is because of our inflated sense of self-importance: we do very little to support our entries, or to hype and preview the show ourselves on British soil, and yet still assume we have some God-given right to victory. "It's a massive disservice to Eurovision – it doesn't take into account the quality of everyone else's songs and the work that's put in," he suggests. "When you look at the other songs, there are good ones, and it’s clear why they'll win. It's not because nobody likes us, it's because we don't have the best song."

Another basis for our apathy, argues Benny, is that our views are simply outdated: Eurovision has developed since we last won, but our perception of it hasn't. "People think it's naff if they've not watched it for ten years, or just have an ingrained attitude that it's crap without even trying it," he continues. "There's a disconnect between the way British people see Eurovision and what it actually is. If the UK treated it like Sweden, or Iceland or Norway, and we got behind our acts, they could develop a career afterwards.

"We’d never treat our teams with such indifference before the World Cup, or Team GB in the run-up to the Olympics. Why is it OK to do that to our Eurovision singers? It's setting them up to fail."

Back at the suite in my hostel, The Independente – which, shameless plug alert, Hostelworld.com kindly hooked me up with – I try to track down some previous UK Eurovision entries. Despite my best efforts to speak to all of our more recent contestants, it seems that – when it comes to Eurovision – none of them have time to talk. Our 2006 entry, however, is a little more obliging.

Daz Sampson didn't intend to enter Eurovision. "Teenage Life" – the song he wrote, which would go on to place 19th the year he competed – was in fact intended for Blazin' Squad to record. "I love Eurovision," Daz says over the phone. "I'm a little older, and when I was growing up I used to be a footballer... [Eurovision] was the equivalent of the FA Cup final."

Daz says he has no regrets about competing, although the monologue that follows is far from a ringing endorsement of the experience.

"Once you do Eurovision, you get put in a pigeonhole and it's difficult to get out of it. Tell me one person in the last ten or 15 years who has had another hit record after Eurovision in the UK. None. We have this thing in this country: once you do Eurovision, you're done. Take the last five entrants – tell me where any of them are. The same thing happened to me. Unfortunately, once you do it you get put in this box, speaking to people like you. In two weeks I'll be put back in the box until next year. That’s how it is. Unfortunately, the people running it for the UK don't have a clue."

Daz says the BBC's team now picks the same type of song each year, and a quick listen to the back catalogue suggests he has a point. "I'll tell [Executive and Music Director for the BBC] Hugh Goldsmith to his face, unless we stop going for safe bets, the same fucking thing will happen," Daz adds, his frustration obvious. "Sorry, I'm getting wound up because it pisses me right off."

SuRie seems calm when I meet her on Friday, just before midnight, the eve of the Eurovision grand final – the three-minute climax that follows months of graft. Just a couple of hours previously she'd been onstage in the packed-out arena, performing for the Eurovision jury, and it's clear she's already taking time to reflect on what comes next. She knows this will all be over after just one more performance.

"You were asking me earlier how I'll cope after the show tomorrow night," she says. "While I appreciate this show, and the fun you get to experience in and out of the arena, it's not the be all and end all for me. There are certain reins that are on when you’re doing this, especially with the BBC, and they'll be off come on Sunday. That's a really nice feeling."

I ask what compromises she feels she has had to make, beyond the fact this singer-songwriter, much more at home in front of a piano, will tomorrow give a glitzy Europop performance. "Doing Eurovision with the BBC is a fascinating process," she replies, pausing briefly. "They're a public service broadcasting company – they can't endorse products. Essentially, I'm a product, so they can only support me so far." Take SuRie's Eurovision single: its release is a requirement of competing, but SuRie explains the BBC can't help promote it or push it out. "Everything they can promote is for the BBC shows, not brand SuRie," she says, matter of factly.

"With the Belgians it was artist-led – they found an artist they wanted to support and promote; the songs were then written for that artist specifically, and with that artist in a collaborative process. I've not had that same experience – it's just different."

Despite not being a BBC employee, SuRie has also been obliged to adhere to the corporation's impartiality rules while competing. "I'm allowed no political opinions, but there are a lot of political questions at Eurovision, and I have to stay completely neutral," she says. "I can't give opinions as it doesn't align with the BBC way."

Back in London, I'd brought up the financials of representing Great Britain with SuRie, having assumed there would be a substantial contract and pay package given the workload she has to take on. "I get a one-off fee for the show itself, but that's it," she’d told me bluntly. "I just need to survive. If I had a waitressing job they'd have said, 'Keep your shifts and we'll work around it.'"

Down in the hotel lobby, as I wait for my cab, I see the BBC's Eurovision team relaxing in the bar. Behind SuRie is a massive corporation, but the very nature of the Beeb means that it has to look out for itself. SuRie, however, is the one putting her reputation on the line – not those behind the scenes. Whatever happens tomorrow night, this will likely forever be seen as her defining moment. Without complete artistic control, it must feel a little like being trapped.

There are certain things which never really change at Eurovision, whether the competition is being held in Kiev, Lisbon or Madrid. There are norms and rituals repeated, in part, because of the obsessive nature of those involved in the Eurovision cult. This is also because, unlike most other international spectacles on this scale, Eurovision is an annual event, and therefore necessitates a more repetitive, military-style operation.

Part of this is down to the geography of Eurovision, the spaces which pop up in the venue and city, irrespective of where it is held.

There's the greenroom, the area rammed with sofas in the centre of the arena, where competitors nervously wait once they’ve finished their set, until the cameras once again turn their way as the results roll in. There's the press centre, where an hours-long line will form on the day of the final, as bloggers queue to get their hands on any leftover merchandise to sell on eBay. Eurovillage, in the city centre, is a hive of cultural activity for those without tickets. The Euroclub is a den of debauchery – an exclusive late-night party venue for those with the right lanyard around their necks.

It's in the "delegate bubble" – a maze of dressing rooms, filled with the music and nervous laughter – that you'll find Eurovision contestants and their entourages in the final minutes before their performances.

SuRie is alone when she opens the door to her thin-walled dressing room on Saturday evening. It's 6:30PM, a couple of hours before her big moment. Hair and makeup completed, she's taking some time out before a vocal warm-up, or so it says on the handwritten schedule pinned up by the mirror.

Whatever her future holds, it's highly unlikely SuRie will ever perform to this number of people again. The BBC team – who I expected to be running around for her – are nowhere to be seen. "I asked them to give me some space," she tells me.

"I remember the comedown blues from past years," she reflects, looking at her herself in the mirror. "This year will probably be even harder because of my elevated position. Eurovision is an incredible show and platform, but it's not make or break for me. I think it’s good; we’ve worked solidly; and then life continues. It's going to be fine, I hope."

Aware that this is the final time I'll speak to SuRie before it really is all over, I want to ask her the question that has been playing on my mind all week: is she worried that, from now on, she'll just be "that woman who did Eurovision"? But to spring that on her moments before she steps in front of 180 million people feels a little too much like sabotage. So, instead, I ask if she fears that, when she's done, her artistic integrity might be in jeopardy. I've not forgotten that "Storm" – the song she'll soon be singing – isn't one she wrote herself.

"I just have to stay true to myself in the performance," she says, smiling. "Obviously if people haven’t watched it, there’s nothing I can do, but if they just give me a chance? The single I’m going to drop afterwards is not a Eurovision track. If people just take a punt, I can show them what I can do. If people don't want to, that’s totally fine. I’ll do what I can to stay true to myself. If people like that, then amazing – and if not, then what can I do?"

A knock on the door signals it’s time for me to get moving. We hug as I wish SuRie good luck, her vocal coach stepping inside. Back outside, in front of the arena, 11,500 ticket holders are making their way through security. There's a buzz in the air, and for the first time I’m caught up in it, as I head to watch the final in a packed-out city centre square.

There are a number of reasons why the UK never does well at Eurovision: we pick mediocre songs and hand them to singers who, if SuRie's experience is anything to go by, we refuse to treat as artists. The British public see the competition as a bit of a piss-take, and it's fair to say we're not exactly popular with our neighbours.

Generally, that's not that big of a deal: Eurovision is frankly a little bit naff.

For the musicians who grace its stage, however, it's a once-in-a-lifetime opportunity. Whatever happens on the night may well define your career for years to come. Halfway through SuRie's performance this year, a stage invader rushes on and garbles what sounds like, "Nazis of the UK media, we demand freedom," into the mic, before he's bundled off and SuRie continues (she later tweets, "Well, I've always said anything can happen at Eurovision..."). The United Kingdom comes in at 24th place, out of 26.