If you are thinking of staying in Oxford for the Friday and/or Saturday night there are plenty of rooms to be found in and around the city. Parking is expensive, so you might want to consider using one of the park and ride facilities around the city.
Accommodation is again fairly expensive, as you would expect from a tourist city. Many of the delegates will be staying at Keble College, which is a short walk from the venue. You can book a room here, or at one of the other colleges via universityrooms.com.