You don't say which course you have had an offer for, but it would be interested to hear. I used to work at one of their campuses, so please send me a PM if you have any specific questions.
BTW, if you want to have a general look at the campus facilities (eg Student Union, the outside of the different buildings, halls of residence etc) you can do this by booking a campus tour, these are lead by students who are very honest and approachable and the best source of information.
And last but not least- congratulations. Oxford is a fantastic place to discover and there will be lots of other students!