We have stayed at Bladon Chains albeit some time ago.
Apart from visiting Blenheim Palace, it is easy to get into Oxford. Drive towards Oxford and use the Park and Ride which is about a mile or so on the left. The bus takes you into the centre of Oxford and one can spend a day just wandering around the different colleges and generally soaking up the atmosphere of the place.
If one goes when the students are not there, speak nicely to the porters in the college lodges and ask if you may go into the quad and take some photos. I have never been refused yet and the college buildings are really beautiful. If you go when the students are there, the dragons on the gates will try to eat you so it is not worth the bother asking.
There are plenty of things to see and do and myriad pubs. There is a tower near the centre which gives one a lovely panoramic view of the city.