Almost every Oxbridge college has a Varsity Trip college rep. They should be your first port of call for any questions or queries you might have about any aspect of the trip.
You can get in touch with your rep by email, or find them on Facebook, before term starts, or you can find them at college freshers' fairs or arranging get-togethers in your college at the start of term. Your rep will be a source of information and helpful advice right up to the start of the trip, and during the week itself, so get to know them now... we chose them carefully, they don't bite!