A cold autumn day on a film set in South London. Ralf Little, the 28-year-old star of the TV comedy staples The Royle Family and Two Pints of Lager (and a Packet of Crisps) is waiting patiently to shoot his first nude scene for the film The Waiting Room. The lights are adjusted, the cameras are checked, but Little can’t bear the tension. “Look, guys, I’m sorry but . . .” he says, suddenly turning to the cast and crew and dropping his gown, revealing himself naked to the world.

“I had to do it that way,” Little says months later, nursing a beer in a Manchester hotel bar. “It was building up to this moment where they’d say, ‘Action!’ and my gown would come off. The fear of that moment was too much. And a part of you hopes they’re not going to go [points to his own groin]: ‘God, that’s rubbish!’”

Little’s nudity is a key part of The Waiting Room. It occurs twice, and illustrates the crippling difference between his character, Stephen, an affable male nurse, and his fastidious girlfriend Fiona (Christine Bottomley): he likes to wander round the flat naked, while she doesn’t. Their relationship is emblematic of a movie that examines modern love through the lives of three emotionally withdrawn couples and asks if love even exists. And, if it does, is it worth it?

There is, naturally, a sop to the possibility of true fairytale romance (Stephen eventually falls for Anna, played by Anne-Marie Duff), but in the face of such acutely observed disillusionment it seems like a gesture at best. “I think it’s intended to be uplifting,” Little says. “But I like the idea that it’s darker than that, and it says that life is not that simple.”

Little’s nudity is also a career statement. It is a bold gesture from the Bury-born actor who seems to be daily divesting himself of past images and associations, like so many old gowns. He is no more the tabloid-baiting London party boy, nor is he the sitcom guy – he crucially abandoned Two Pints before the most recent series. He does theatre now, and recently starred in a well-received one-man show called Stacy (about a date rape). This followed his appearance in the two-hander Notes on Fallen Leaves at the Royal Court.

Mostly, though, he’s got Hollywood in his sights. He went out there two years ago and loved it. He played football with Robbie Williams for the Hollywood United team, met industry insiders and got a taste of the high life. This time, inspired by the success of James McAvoy (Atonement), he wants to do it the right way.

“Three years ago me and James McAvoy were going up for the same parts. And now look at him. He’s brilliant. But he didn’t go straight to LA. He did quality films here, and that’s the way I want to do it. And if they get me noticed and I get a different career path that’s great. But I have to do quality.”

Nonetheless, Little has a no-regrets approach to his past. He has watched, unfazed, as opportunities and distractions have fallen into his lap in equal measure. He was, for instance, always going to be a doctor. Acting was just a teenage hobby, like football. The son of two accountants with “middle-class aspirations and a working-class income,” he was studying at Manchester Medical School when the first season of The Royle Family was broadcast (he filmed it during a two-month break from his A-level year). As Antony Royle, later known affectionately as “Lurkio”, he was the family dogs-body and the butt of many jokes.

Unsure of the show’s prospects, though, Little concentrated on what he saw as his real career. “I was 17 years old and 100 per cent focused, and I knew what I was going to do. I was going to be a doctor.”

The show’s success, however, was seismic. With his parents’ blessing Little soon moved to West London and abandoned all medical ambitions. He dated the TV presenter Lisa Rogers. He popped up in the movie 24 Hour Party People (as Joy Division bassist Peter Hook). He even flirted with professional football (he eventually played semi-pro for Windsor & Eton FC).

Mostly, however, he enjoyed himself, appearing in repeated tabloid stories of booze-sodden excess that culminated in a reported two-day romp with a lap-dancer who was “delighted to discover that he was Little by name but not by nature”.

“I don’t mind that story coming out again,” he says, grinning. “At the time it could have been embarrassing, but the story is basically: ‘A young actor’s had sex with a girl.’ Which is fine. And I’m quite proud of myself actually. I never lost my way. Never fell into the drugs trap. And never cheated on anyone. So, yeah, I enjoyed a drink and went out a bit.”

Even so, Little’s lifestyle took its toll in 2004 when, at a charity football match in Belfast after another heavy night of boozing, he collapsed on the pitch and had a fit. “I was hungover and so I overhydrated before the match,” he says. “My brain cells suddenly went wooosh, I had a massive fit in front of 10,000 people, and then woke up in an ambulance.”

Little was not unduly troubled by the fit. His sense of perspective, it seems, is grounded in something larger than that. When he was 9, for instance, his older sister Ceridwen fell to her death during a family holiday in Cornwall. It was a life-changer, and yet not. “It taught me that shit happens, and that you have to get on with life,” he says. “I know it sounds ridiculous. It was my sister, and it was horrendous. But we have all been through shit. Welcome to the human experience! Now get on with it!”

At the moment, thankfully, it all seems to be good shit for Little. He’s single, he drives an Aston Martin, and he’s just finished shooting a musical biopic, Telstar, opposite Kevin Spacey, about the life of the doomed record producer Joe Meek. The movie features Little as a young Chas Hodges, half of the bearded cockney double-act Chas’n’Dave.

The film’s debut writer-director Nick Moran apparently had his doubts. “He said to me, [does flawless East End accent] ‘You do know you’ve got to be a f***ing cockney for this, don’t you?’ And I said, ‘Yeah, is that a problem?’ And he said, ‘Dunno, you f***ing tell me, you Northern mug.’”

In the meantime, while he’s completing Massive, a Shameless-type drama about an indie record label, for the BBC, and having finished his second co-written online novel, The Boy with a Thorn in his Side (about guys who get dumped), he has just enough time left to contemplate the limits of his starry Hollywood future. Beverly Hills mansion or Bafta award-winning role? “Can’t I have both?” he asks, dead serious, as if they’re about to be produced from under the table. “That’s the funny thing about that. They can go hand in hand.”

He double checks, as if he’s made a mistake. “Can’t they?”

The Waiting Room is released on June 6 2008

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