The Marriage Ceremony will begin at 2pm in St. Mary's Church, Oakley, Buckinghamshire. The village of Oakley is between Bicester and Thame, and the Church is on the Bicester Road that leads from one town to the other. There is not a lot of parking available outside the church.
Also on this site there is information on where you can stay in Oxford. The University offers accommodation at a reasonable price, and will mean that you do not have far to go when the reception ends.