From her humble beginnings in Australian soap opera Home and Away, Isla Fisher is fast becoming one of Hollywood's hottest up-and-coming female talents. The 31-year-old mother of one talks comedy, her nomadic lifestyle and Sacha Baron Cohen

You seem to be carving a niche for yourself in comdey...

Isla Fisher: It was mainly Sacha that got me into it. At school I was the class clown. I have always been the one to make a fool of myself to get a laugh at a party or wherever I have been in my life. But I have never really associated that with doing it publicly in such a large arena.

But then Sacha was like, 'You are so funny, you are the funniest woman I know - you should be doing comedy.' After that I auditioned for Wedding Crashers. Sacha is so funny that he sort of inspired me. And since I started doing what I like to do on camera, I have had a lot more success. When you try to suppress yourself and be really serious, people just don't buy it.

Are you surprised to be playing more mature roles? You still look so young!

Isla Fisher: I know, I know, I'm old but I look young! Actually, it has caused some problems in the past. We went to a party in Hollywood when we first came over and it was a big celebrity thing and we were really excited. I got to the door and this posh woman ushered us in to this huge mansion and then she took my hand, let Sacha go into the party and took me into a separate room. I'm like, 'Oooh, am I going to get a goody bag?' and the room was filled with 13-year-old kids! She said, 'Do you want a soft drink?' and then it sunk in!

Was it always your goal to make it in Hollywood?

Isla Fisher: No. Weirdly enough I only came out on the back of Scooby Doo for the premiere. Then I ended up getting representation and getting a job almost straight away. I was fortunate in that I didn't have to come out to LA and join a queue of however many people and try to get work. I came in on the back of what was deemed a big studio movie that had had extraordinary success.

Are you happy living in LA?

Isla Fisher: I don't really live there; I live 50 per cent of the time in London and Europe. I'm Australian so that's home too. I'm a bit of a nomad.

A lot of Americans don't seem to know you are Australian...

Isla Fisher: When you go to have meetings, usually before you audition, they'll chat with you and it always feels really contrived and awkward for me to conduct that conversation in an American accent. So I go in and say, 'G'day, I am Isla' and then when I start acting I'll do the accent. When we filmed The Lookout, I would stay vocally in character through the day, just to keep my American accent up.

Isn't Isla a Scottish name?

Isla Fisher: Both my parents are Scottish. I'm named after the island of Islay where they make whisky! But I grew up in Western Australia, in Perth.

Do you hang out with other Aussies in Hollywood?

Isla Fisher: Naomi Watts has given me great advice. She's very sweet and very nice, and you get rejected a million times. She'll always say, 'Just don't get tired.' She's great.

There is a lot of media attention on you and your fiancee. Is that hard to deal with?

Isla Fisher: Not really, because I never talk about my private life. I have never answered questions about my personal life, ever. There has been a tiny shift in awareness but it hasn't really affected me in any way yet. I haven't had a situation where I have gone out of the house and felt as though I was being followed.

Sacha caused quite a stir with Borat. How did you feel about that?

Isla Fisher: I guess it's like anyone who has a relationship with someone who does things that create situations. I try not to think about it. But I am relieved the movie's over. Our relationship went through a very strange patch where, instead of normal conversations like 'Hello honey, how was your day at work?' it was 'Honey, did you get beaten up? Did you get arrested? Did you get a big fat man sit on your face? Are we being sued?'

Have you set a date for the wedding yet?

Isla Fisher: No, not yet, there's no date yet. I'm not about to give away any big exclusives about that! It'll happen when it happens. And when it does it will be our day, no one else's. We're definitely going to have a traditional Jewish wedding, I can say that.

Is the height difference a problem? You?re 5'2" and he's 6'3"...

Isla Fisher: I'm used to it. It used to be hard when we went out to a bar or something, or when we see friends. People try to pick up little people physically and they pat you on the head. I always get picked up. I think it's like when I communicate with a dog or something that's low down, I like to get down on the level. It's well-meaning but the pat on the head or the lift is always hard.

Are there any plans for you and Sacha to work together?

Isla Fisher: I don't see why not. There aren't any plans, but I think all couples really end up collaborating on things anyway. We help each other out. And he definitely makes me laugh more than anyone, which is why I'm marrying him. So yeah, I don't see why not.

Is it true you went to clown school?

Isla Fisher: I did, indeed. Well, I went to a prestigious theatre school called Jacques Lecoq where Geoffrey Rush went. I think it's an unusual choice but I really am glad that I did it. Sacha and I both went to the same school. It's just a great way to learn physical comedy like mime...and how to juggle! Juggling is under-rated.

What do you find funny?

Isla Fisher: I love to do harder stuff. I can't lie; I am the first one to enjoy a very dark joke. I love Monty Python and I am obsessed with Black Adder and mainly my taste is pretty subversive and dark.