I've picked up a lot of Britishisms in the two years we've been here, but more the terms rather than the pronunciations. Some of the pronunciations I do use (zeh-bra, for example) are more for my three-year-old's benefit, so his friends at school will understand him! I don't know why some terms I'm comfortable with (I say "pavement," "bin," "pram" etc) but others just feel weird - like I can't say "loo" or "cheers" without feeling fake.