Right well, I'll tell you what me and my housemates wore...I wore a black pinstripe trouser suit with a red jumper and red shoes, one of them wore a black cocktail dress and a pretty pink necklace, all the others wore black/grey/navy skirt suits, shirts black/purple/blue/white and heels as far as I can remember. Our college recommended you bring a suit, or else something else equally smart. At most most of the colleges you have to wear a gown though, so I don't imagine anyone can see much of what you are wearing underneath. Which college are you from? Most people will be too hungover to care anyway, being in the middle of freshers week!