^ Indeed, just be yourself. If you don't get on with them, or they don't get on with you, it'd be far worse in the long run to be IN the band!
As contrite as it sounds, don't get too het up. It's a little like an exam, and I always found that the best exam technique is to have done your revision in advance, and to make sure that on the day you're as relaxed and chilled out as possible. Try not to stress about it when you're there, it's most important to be relaxed and to be "you"!
Good luck, and I hope you all gel together - that's the key thing!
Roo