ONCE upon a time, Nicholas Hoult was a young British boy who starred with Hugh Grant in About a Boy.

Grant had a sexy new crop while his 12 year-old co-star sported a rather unflattering pudding bowl chop. But that was 2002, before Hoult morphed into a strapping 6ft-tall star. Boosting his street-cred in Channel 4 series Skins and hip urban film Kidulthood, he then won kudos for playing limber mutant Beast in Matthew Vaughn's hit comic-book prequel X-Men: First Class and, doubtless, admiring glances for dating co-star (and recent Oscar-winner) Jennifer Lawrence.

So it's no surprise that when this affable 23 year-old from Berkshire arrives at London's Mayfair hotel on a dark winter's evening, he's looking like a man enjoying his very own Hollywood fairytale. Back from Namibia for just the weekend, he's in the midst of filming Mad Max: Fury Road, the long-awaited fourth instalment of the post-apocalyptic series, which explains away his current crop – a skinhead. "It gets this Velcro-like texture to it, and things stick to it," he laughs, rubbing his fuzz. "You find bits of fluff in your hair the whole time."

Hoult may be lurching from one bad hair day to the next, but his career is in rude health right now. Recently, he took the lead in Warm Bodies, a zombie romance from the company behind the Twilight movies which has already taken over £57 million around the globe. Now comes Jack The Giant Slayer, a £135 million twist on the classic tale of Jack and the Beanstalk from Bryan Singer, the director of such big-scale blockbusters as X-Men and Superman Returns.

Hoult plays Jack, a simple orphan farmhand who falls for the spirited Princess Isabelle (newcomer Eleanor Tomlinson). "He just completely falls head over heels for her, but doesn't think he has a chance." With this fair maiden spirited away to a land of giants, via a particularly fast-growing beanstalk, Jack winds up accompanying the rescue team, led by Ewan McGregor's impossibly brave knight Elmont. "It's a good family romp," he adds. "There's the romance and the adventure and the epic scale of it, and the world that you get taken into is really spectacular."

It's not hard to see what appealed to Hoult about playing Jack. "He's a bit of a have-a-go hero and there's definitely that aspect of my personality, of trying to prove something to someone." Whether that includes being able to lead the line on a Hollywood blockbuster he doesn't say – although the film has not been without its problems. Due out last year, but then moved by the studio to allow Singer and his team more time to work on the special effects, there was also a title change – rather pointlessly – from Jack The Giant Killer. So far, the film has taken a disappointing £19 million across its opening three days in the US.

So does Hoult feel pressure, fronting such a large movie? He nods, considering the question for a minute. "You're in the middle of what is costing a lot of money and you don't want to mess it up," he concedes. "Hopefully people won't blame me if this doesn't work." Hoult knows, however, that he wouldn't be the first to feel the weight of expectation. "I read an interview with Daniel Craig the other week, and he said he still feels pressure playing Bond, even though he's done it a few times and he's obviously great at it."

LIKE Craig, Hoult offers a very physical presence on screen – from his acrobatic turn as Beast to the demands of Jack, which required him to take horse riding and climbing lessons. He's also proved quite adept at changing his appearance. "I've done it in a really subtle way," he says. "I gained quite a few kilos of muscle just working out for the X-Men film. I thought I was a bit too scrawny to play Beast. And in Mad Max, we're meant to be living in a world where we're not very well fed, so I dropped 10 pounds for that. It's good – it gets you in the right headspace."

With his mother a piano teacher and his father a pilot for British Airways, Hoult never had a way into the industry; he simply followed his older siblings, James and Rosie, into amateur theatre. "I was lucky enough to be the third one along out of four," he says. "What they did carved a way for opportunities to arise for them, and I got sucked in." By the time of About a Boy, Hoult was studying at London's Sylvia Young Theatre School – though a later return to secondary education didn't seem to hamper his career. "I've been fortunate so far to be able to make the transition from acting as a kid to still working as an adult," he reasons.

Whatever the fate of Jack The Giant Slayer, he's done more than just pay the bills. Playing a young warrior named Nux, Mad Max: Fury Road will pit him alongside Tom Hardy (who replaces Mel Gibson as Max). Then there's another Bryan Singer reunion on the second X-Men prequel, X-Men: Days of Future Past. If this will also reunite him with his former flame, and girl-of-the-hour Jennifer Lawrence, Hoult seems unruffled. Even with that eye-catching buzz-cut, he reckons he can keep his head down. "I'm fortunate that I can keep under the radar. Maybe that's partly to do with how you live your life, what you do and where you go."

Carry on like this, and Hoult will live happily ever after.

Jack The Giant Slayer opens on March 22.