Richard Ayoade has joked it was difficult to mess up his first feature film - because the book on which it was based was so good.
The IT Crowd actor had previously only directed music videos before taking on Submarine, but said he knew when he read the novel by Joe Dunthorne - which focuses on a troubled schoolboy in Wales - that he would be able to direct a film.
Speaking at the film's premiere at the BFI London Film Festival, he said: "I just thought it was very funny. I thought the book was good enough that no matter how much lack of ability I brought to it, it couldn't be fully screwed up. That was my motivation."
Young actor Craig Roberts also makes his feature film debut in Submarine, playing the lead role.
The 19-year-old said the experience was nerve-wracking but working with the likes of Richard and experienced co-stars Paddy Considine and Sally Hawkins made it easier.
"What a first film to be in - with Paddy Considine, Sally Hawkins, Noah Taylor, Richard. It's great," he said.
"I'm a huge Paddy fan. I think we all are. He's such a professional - he's great. He uses a lot of improvisation. I was thinking, 'how is he doing this all the time?'. He's amazing - well done Paddy, you're amazing."