Rob Kazinsky – or, as you, your nan and your mum probably call him, that bad boy Sean Slater off EastEnders – is describing his first LA audition. "It was for a big, big movie," he says. "I was so excited to be at an American audition. There were hundreds of actors there, all better connected, better looking and more talented that me. As I walked into the audition room, there was a sign on the door saying: 'DO NOT SHAKE THE CASTING DIRECTOR'S HAND'. I thought, 'That's weird, but OK.' I walked in, and the casting director put their hand out to take my CV and headshot, and I shook it. Just automatically! They were very nice about it. But everyone I spoke to afterwards said, 'You just don't do that here.' I didn't get the job."

Countless times, UK soap actors have flown out to LA clutching their Soap's Sexiest Villain award, shouting, "I'm going from Hollyoaks to Hollywood!" only to limp back in six months, clarifying that they really meant "…for a holiday", and what they actually wanted to do all along was go on Celebrity Big Brother. Yet in 2013, US TV is packed with soap actors who've quietly left their double-crossing, family-feuding characters back in Blighty to make a proper go of it.

Kazinsky quit EastEnders in 2009, and says he moved to LA out of the necessity to find more acting work, rather than out of any hubristic dream to break America. "I spent eight months auditioning in England, and no one would give me a job," he says. "I was broke, so I did a Radox advert and became a car mechanic. But then I landed a small role in [George Lucas's] Red Tails and moved to LA. I spent another 18 months auditioning here: nothing. But finally, out of nowhere, I landed some parts and it's all just snowballed from there." He'll also appear in Guillermo Del Toro's Pacific Rim this summer.

"Every actor who comes out of a British soap will experience that in some form or another," affirms Nathalie Emmanuel, formerly heroin-addicted teen Sasha Valentine in Hollyoaks, soon to be appearing as slave/translator Missandei in the new Game Of Thrones. "People can't see you in any other role. So you just think: why not move to another country?"

Emmanuel left Hollyoaks in 2010, while Judi Shekoni – recently seen in Twilight: Breaking Dawn Part 2 as near-naked Amazon vampire Zafrina, but "constantly recognised, even in America" as gangster-girlfriend Precious from EastEnders – has spent "six or seven years" in LA doing small parts. She only landed her Twilight audition when she spotted the ad in a trade mag. "I'll go for an audition where they want a British black or mixed-race girl, and I'll think, 'I've got this one down.' Then I turn up and there's 25 girls just like me. I'm like, 'How is this possible? I moved to the other side of the world!' There are a lot of British people out here now."

It's no secret that America loves Brits. Gossip Girl, The Wire and Homeland all featured UK actors in lead roles, and House's Hugh Laurie is US TV's second highest paid star. But while the Downton Effect benefits Cumberbatch and co, ex-Hollyoaks stars don't exactly fit the foppish British stereotype beloved of US casting directors. As well as Emmanuel, there's Barry Sloane, who's swapped being Chester's resident psycho Niall (you remember: blew up a church to kill his own sister) to play the mysterious Aiden in Revenge; and Max Brown, who's starred in everything from Grange Hill to The Tudors, is now playing a womanising doctor in the CW Network's Beauty And The Beast.

There must be another reason why British soap actors are suddenly in demand. Emmanuel has an inkling: "I think soap actors are totally underrated on how hard they work: you're prepared to go the extra mile to get the job done. When you go out to the States, it's almost like starting again, so if you look right and do the part well, then you have a shot. Plus, you want to prove the fact you can be something else other that your previous character."

'In LA, there are a lot of people who want to be Kardashian rather than an actor. Coming from the UK, you just don't think like that, and that generally goes down well' Rob Kazinsky

Rob Kazinsky as Sean Slater in EastEnders. Photograph: BBC/Adam Pensotti

Years of putting in the hours on low-budget TV productions appears to have provided these Brits with the requisite toughness for surviving the notoriously unforgiving Hollywood machine. "A 5am call time is nothing, because I'd have been driving myself to the Hollyoaks set at 5am," says Emmanuel. Kazinsky agrees that if you're used to queuing in the cold for the catering van, you're unlikely to let the comparatively lavish American set-ups go to your head. "On sets, there's always someone who'll get upset with me if I try to make my own cup of tea. They'll say, 'That's my job. I'm paid to do that.' I have to explain that, where I come from, you make your own tea. In LA – and this is generalising a lot – there are a lot of people who want to be a Kardashian rather than an actor, so they're expecting to be treated like a celebrity. Coming from the UK, you just don't think like that, and that generally goes down well."

There are, however, other culture shocks to overcome. "In the UK, producers tell you not to get drunk and blab the EastEnders storylines in the pub," says Shekoni. "In LA, they say, 'Here's a 10-page confidentiality agreement, and if you break it, you owe us a million dollars.' You're so stressed out that you can barely speak. I was scared to even say my own name in public. When pictures of the Twilight wedding dress went online, we all lost access to the internet from the set for a few days so nothing else could get out." Kazinsky couldn't even tell his parents when he landed his True Blood role.

While, in the UK, any burger bulge can be hidden beneath the bar in the Queen Vic (or even written into the storyline), when you get to LA, the pressure to look good is intense. Shekoni recalls seeing her Twlight outfit – basically a loincloth – for the first time: "I thought, 'Right, I need to start working out.' If I had to be on set at 5am, I'd be in the gym at 4am. On EastEnders, however small Precious's outfits were, I'd have never been in the gym at 4am. I would eat fish and chips the night before."

For his role in Pacific Rim, Kazinsky put on 40lbs of muscle and got down to 6% body fat by eating seven full meals a day. "I was taking in 12,000 calories a day and working out for five hours a day. And now I'm training for True Blood, I'm working out six days a week. In the UK, I'd go to the gym maybe once every few weeks."

He recalls an emotionally scarring incident from 2011. "I did two episodes of Brothers & Sisters, and the script said, 'He takes his shirt off to reveal a rippling six-pack.' I only had a week before filming to do as many sit-ups as I could. I tried so hard. But on the day, I took my shirt off and there was silence, everyone turned their heads to the side and said, 'Oh well.' They had to 'work around' how my body looked. It was so shaming."

Although Kazinsky has successfully proved that there is life beyond the UK soaps, he's well aware that landing a Hollywood role is not an instant passport to fame and fortune – or even professional satisfaction. He even suggests that the best actors he's appeared alongside might still be back on the Square. "I've worked with Oscar-winners and Golden Globe-winners but still the best actor I've ever worked with is still Jake Wood [EastEnders' Max Branning]. There's this stigma attached to working on a soap, like you're a bad actor just because you're on one. But if you can be good on a soap, you can be good on anything."

Six Brits who've struck it rich on US TV

HUGH LAURIE Earns £250k for each episode of House; rather more than he made from that jazz album.

DAMIAN LEWIS Earns £47k per Homeland episode; a small price to pay for all those pained looks.

CHARLIE HUNNAM Revealed that for his first episode of Sons Of Anarchy, he "got paid twice what I got for all of Queer As Folk".

STEPHEN MOYER Vampire Bill from True Blood gets paid around £126k per episode; that's a grand every time he takes his top off.

ANDREW LINCOLN Killing zombies in The Walking Dead earns Egg from This Life around £25k per episode.

LISA VANDERPUMP What do you mean, who? This Real Housewife Of Beverly Hills gets paid £157k per season of the reality show.