Thanks to David for letting me know there is a beer festival at the Plum Pudding (formerly the Admiral Benbow) in Milton village this coming Saturday and Sunday (4th/5th April).
This is a pub I have heard good things about recently. It used to be a Greene King pub, but has more recently become a freehouse and community village pub serving at least 4 real ales. See the Campaign For Real Ale (CAMRA) WhatPub website for more info
It is an fairly easy cycle ride from Abingdon, and a beer festival sounds like an ideal excuse to visit.