Two bus companies operate a regular bus service from London leaving every 10/15minutes from Victoria calling at Marble Arch and other stops in London. It takes about 1 and three quarter hours to reach Gloucester Green in the Oxford City centre. They operate throughout the night.
There is a train service between Oxford and Birmingham airport.
There is a regular train service between Oxford and London Paddington that takes about an hour (except for some slower trains). Do check the Sunday service before travelling. There is also a train service between Oxford Parkway station and Marylebone. Oxford Parkway is on the outskirts of the City located at a Park and Ride Car park. It goes via Bicester Village designer outlet shopping centre.
Parking in Oxford is very limited and on street parking is often only for 2 hours. The best advice is to use one of the city’s 5 Park and Ride car parks where you can park all day for a small charge. At the Thornhill Park and Ride it is possible to park for up to 72 hours. There is then a very frequent bus into the City centre. For timetables check at www.parkandride.oxfordbus.co.uk There are car parks in the centre at Gloucester Green, Worcester street and Oxpens.