Hi,
I haven't really posted much but I thought I'd chime in since I've been a student here for the last four years and know the city really well.
Since this is style forum I suppose I should start sartorially. It terms of casual dress Oxford is much like any other university so you can pretty much wear whatever you please, no one really cares at all. I guess people generally dress on a day-to-day level more nicely in Oxford than some places but, yeah, there is nothing particularly unexpected. There are however loads more opportunities to dress up than anywhere else. Depending on your college you will definitely get quite a few opportunities for black tie, summer cocktail parties, boat club drinks etc. So you can have loads of fun with all these events. So far this term, now we're in week three, there have already been at least 5 different college parties with varying degrees of formal dress code and some people really do make loads of effort with their clothes. It's definitely somewhere you can be pretty dandyish without attracting any negative attention.
In terms of actually buying clothes Oxford isn't all that great. My personal love (due to a student budget I guess) is second hand clothing and there really isn't much, a decent antique market on Thurs with some vintage clothes stalls, some okay shops on the cowley road and the usual smattering of charity shops. Obviously if you have money there is Ede and Ravenscroft for beautiful suits and Ducker and Sons for expensive shoes.
Depending on what you're into Oxford is a really amazing place, as was mentioned there are pretty great music venues, loads of pubs, some lovely little restaurants. Just don't get too bogged down with all the terrible chain stuff in the centre...
Anyway, if you want some tips on fun places to hang out just PM me and I'd be happy to help out (especially if you're into music), or I dunno, if you just want some general advice. It really is one of the best cities in the world, especially in the summer, so you should have an amazing term.