By all accounts the ozzy one was turn up on the day, and a few people have said it will be the same for the uk ones too.
Direct quote from the e-mail I had:
But it's only London - head down and have a dabble, what's the worst that could happen? They'll probably admire the balls.The Ultimate Fighting Chamionship has selected you to take part in our private tryouts for The Ultimate Fighter Australia vs. UK 'The Smashes'.