i think the other thing to remember (and i'm not trying to rain on anyone's parade here, i just think it's fair to point it out) is that oxford/cambridge is liable to be a LOT more work. and you have a lot more people who have straight a's (i.e. almost everyone) versus most other universities where the entrance requirements for physics are liable to be a lot lower.
Yes, a cambridge degree is probably worth a lot more than one from a "normal" university- but is a worse degree from cambridge (say, a 2:2 or third) worth more than, say, a first from a well-respected, but not oxbridge, university?
I'm not saying you'd get the worse degree, obviously, but you know what i mean. A lot of jobs state you must have a 2:1. I don't know, there may be leeway if you went to oxbridge, but there may not.
Worth thinking about, i guess.
EDIT: bear in mind, I'm extremely lazy, and the "extra work" part of it would really annoy me. It may not annoy you. :lol: