Lena is head-ey over heels

The Parole Officer is the first big comedy I've done - I'm the romantic interest. I play a policewoman and Steve Coogan is an incompetent probation officer who's framed for murder. He's a more normal version of Alan Partridge - a snoggable Partridge.

We talked a lot about the reasons for my character fancying him. He's eccentric, with an intriguing sense of humour. She's had boyfriends who are only interested in themselves - and he's totally different. They'd make a go of it as a couple, but first they'd probably need some dancing lessons.

I didn't prepare by meeting any policewomen. You put the uniform on and make your hair neat - that was the closest to Method acting I got. I enjoyed wearing the uniform - it looks cool and the gun-belt made me feel more responsible, a bit like Lara Croft. Steve's like all his alter egos rolled into one. He's intense and serious about the work, but sometimes he'll go off on a comic riff for the film crew.

It was hard to keep a straight face in our romantic scenes. I was desperately trying to make him laugh, too, when I was off-camera. He gave me lots of directions for the comedy - sometimes too much. It was helpful, but I felt a failure if I couldn't make him fall around laughing. In the end, I gave up and did what felt true.

I was worried about my performance because I'd not done anything this light. It felt odd that I wasn't exhausted at the end of the day or still going over stuff in my head. But, now that I've seen The Parole Officer, I think it's uplifting, fun and honest - it doesn't pretend to be anything and that's refreshing. You enjoy all the characters and the film gives them time to develop, so that you get to care about them all.