The man the NME once referred to as the coolest in London sits in the Soho offices of a film distribution company, wearing a blue polka-dot shirt and an expression of absolute mortification. The offices are at his disposal because they're working on his directorial debut; the expression stems from the fact that I've just told him about that NME accolade. "When did that happen?" frowns Richard Ayoade. "Right. Well, that's an error. I've no idea why they would think that. That does seem to be a category error. That's all I can say about that."

But then again, it swiftly transpires that being mortified is very much Richard Ayoade's thing. He seems embarrassed by almost every aspect of his past, whether as president of Footlights at Cambridge – "It was incredibly uncool, so I got it completely uncontested" – or as the actor who created the role of Maurice Moss, the beloved über-geek in the IT Crowd. For one thing, he was apparently the weak link in an otherwise stellar cast ("The others are really good actors, so it can contain something which is more of a turn than an acting performance – I wouldn't dignify what I do by calling it acting"). For another, it made people recognise him on the street, which invariably doesn't go well: quietly married to the actor Lydia Fox, he isn't keen to bask in the glory of public recognition. "It's consistently disappointing for anyone who encounters me," he says. "It would feel ungracious to be carping about it, but it's very hard to know how to respond. It's a very odd thing because the IT Crowd is quite popular, and it's also around the world quite a lot. So if you go to Prague or something…" His voice tails off into a sigh. He is what Jerry Seinfeld would have called a low talker. There's a famous story that the director of the IT Crowd told him that Moss was "the geekiest person in the world – so just use your own voice", but in reality he's nowhere near as strident and self-assured as his onscreen counterpart who, it's perhaps worth noting, still lives with his mother, sleeps in his glasses and carries a small water spray with him in case he suffers from a "hot ear".

Furthermore, reading through his old interviews, it seems this is very much the new, improved, media-friendly Richard Ayoade: one journalist who encountered him just as the IT Crowd broke found him "cowering" behind his glasses and complaining that he was "terrible at talking, with words". Today, at least, Ayoade is a little more enthusiastic about the film he's here to promote, Submarine, which he wrote and directed, adapting the story of a teenage misfit and his pyromaniac first girlfriend from a 2008 novel by Joe Dunthorne. Or rather, he's enthusiastic about talking about films generally – the influence on the finished product of Taxi Driver and Badlands and Eric Rohmer's Love In The Afternoon, the time the NFT hosted an Ingmar Bergman season and he saw everything in it, "which was one of the best two months ever" – without ever doing anything to suggest that any aspect of Submarine that's to do with him might be any good. When I tell him I enjoyed the film – which is extremely funny, touching, beautifully shot, possessed of a fantastic soundtrack by Arctic Monkeys frontman Alex Turner and brilliant performances by its young leads Craig Roberts and Yasmin Paige – he mumbles his thanks, but bows his head as he does so, as if he's literally trying to duck the compliment.

He found the film shoot gruelling – "It's like trying to tell a joke by recording one word a day into a Dictaphone out of order and reassembling it and hoping the cadence of it works" – but, he concedes, he'd rather be a director than an actor. "I find performing very difficult. It's difficult to be a good actor. I get very nervous, even though it sounds disingenuous, because you could legitimately go, 'Well, why do it?' Which is inarguable. There's no good response to that. Initially, it was a way of showing writing really. If you're writing for a no-money stage show, you can't just ask people to do stuff for no money, so you end up doing it yourself for no money." This turns out to be another thing Ayoade is big on: suggesting that everything that's happened to him has happened by accident, or at least by default, never by design. "It was all somewhat unthinking. There weren't particular targets that it felt you were reaching or not reaching." At one point, he refers to his career's trajectory, before catching himself: "If it even is a trajectory."

There's nothing defensive or snippy or sarcastic about his tone when he tells you that he can't act, or carries on as if his entire professional life is a kind of complicated mistake: he's actually rather charming company. Nevertheless, it's perhaps just as well that Ayoade is on hand to tell you how resoundingly underwhelming his career has been, because without his commentary, you might easily come to the conclusion that, at 33, he's a wildly successful overachiever, precisely the kind of person the NME might be minded to call the coolest person in London, thanks to red herrings like the string of awards – the Perrier he won at the 2001 Edinburgh Fringe for co-writing the spoof horror comedy show Garth Marenghi's Netherhead; the Outstanding Actor in a Comedy gong his performance in the IT Crowd scooped at the 2008 Monte Carlo Television Festival; the NME Brat Award for At The Apollo – the feature-length concert film he directed for the Arctic Monkeys; and the starring roles in three of the most iconic television comedies of recent years – not just Moss in the IT Crowd, but the belligerent shaman Saboo in The Mighty Boosh and the graphic designer Ned Smanks in Charlie Brooker and Chris Morris' Nathan Barley. After a while in his company, you start to wonder if the continual self-deprecation isn't so much disingenuous as a defence against the accusation that he's had rather an easy ride, without much in the way of due-paying – he doesn't think he's ever really been to an audition, which is perhaps just as well "because I'd be so bad at it" – or the conversational equivalent of an extremely tall person deliberately stooping so he doesn't intimidate those shorter than him. Indeed, the only thing that doesn't seem to have panned out was an attempt to reprise the role of Moss in an Americanisation of the IT Crowd: the pilot was never broadcast. "It was picked up, and then I think the head of NBC left and there was a regime change. So it was a slightly odd thing where, being naturally pessimistic, I assumed it would never happen and then was very surprised when it seemed like it would. Then I had to start thinking, 'Oh, do I have to move to America now?'"

He was born in Ipswich, an only child with a Nigerian father and a Norwegian mum. To hear him tell it, his parents' nationalities were unquestionably the most exotic thing about his childhood, unless you count the time he saw Louis Malle's nouvelle vague comedy Zazie Dans Le Métro on Channel 4, which set him off down the path of the film nerd, and the fact that he wrote plays and comedy sketches, one of which was performed at his Catholic boys' school. "I imagine it wasn't well-received. I'd hope it wasn't. It was pretty weak and I'm sure there was a level of politeness that someone had bothered to type out that amount of words, but that was probably all it deserved."

He went to Cambridge to study law, again by default. "My parents didn't go to university and weren't brought up in England. They hadn't heard of any other universities other than Cambridge or Oxford. It was just through a kind of ignorance that I somehow managed to get in. I wasn't really intending to study law, but the idea of doing a non-vocational degree just seemed somewhat, you know… Regency-era. Indulgent. Unacceptable. The idea that you would go and study English or philosophy or something as some manner of broadening your mind was completely out of the question really."

He became a member of Footlights during what he depicts inevitably as a nadir for the august comedic institution, despite the fact that his fellow members included David Mitchell and Ayoade's former writing partner John Oliver, now the Daily Show With John Stewart's Emmy-Award-winning British correspondent. "Well, the nature of television comedy had taken a massive leap with The Day Today and Alan Partridge, and sketches were pretty out of fashion. It's a young age to be doing comedy. You're not coming on as some world-weary Hancock figure – no gravitas, no life experiences."

After graduating, he spent two years writing for TV sketch shows and attempting stand-up: the latter, it scarcely needs saying, went badly. "I found it terrifying and I was poor at it. I think it's hard to have the objectivity to create a persona that gives the illusion of being you but isn't. I always felt uncomfortable doing it until it started being characters. I find it very hard to come on as a funny man saying things," he adds, which is why he doesn't do the usual round of TV panel shows, a recent appearance on Channel 4's Big Fat Quiz Of The Year notwithstanding. "I did that because Noel Fielding was doing it and I know him and could feel, you know, comfortable." I tell him he was funny on it and he makes a face. "I don't know. I haven't watched it. I'm not good at watching myself."

During the abortive attempts at stand-up, he kept writing about the fictional horror author Garth Marenghi with Matthew Holness, which proved his breakthrough: not only did the second Marenghi stage show win the Perrier Award and a contract with Channel 4, but while performing it at Edinburgh, he met Noel Fielding and Julian Barratt of The Mighty Boosh. He developed a parallel career as a rock video director after mentioning in a meeting with record label and film company Warp that he loved the Arctic Monkeys, and ended up directing a string of videos for them (given the band's legendary reticence, the mind boggles at what the initial meeting was like) as well as Vampire Weekend, Kasabian and the Yeah Yeah Yeahs. Mention of it brings on another attack of modesty – "No matter how bad a music video, the song remains intact" – but his videos are weird and intriguing. He dressed the preppy, hip Vampire Weekend as goths, and somehow transmuted the Arctic Monkeys' Fluorescent Adolescent into clowns engaged in a violent pitched battle with non-clowns, shot in the style of The Sweeney. Furthermore, it led directly to Submarine. It was Warp that optioned the novel and suggested Ayoade direct it.

Initial reactions to Submarine have been strong. He's about to take it to the Sundance Festival, which involves an audience Q&A, something you imagine Ayoade isn't exactly bowled over about. And he's already got another project lined up: he's working on an adaptation of Dostoevsky's The Double. "A sort of doppelgänger tale, and funny, I think. Very funny. Dostoevsky never finished it to his satisfaction, which is somewhat…" His voice tails off, and when it returns, for once, there's a hint of sarcasm. "So yes, we're going to dust that off," he says heavily. "We'll do what Fyodor couldn't."

• Submarine is released in the UK on 18 March.