If I remember correctly it is £50 per month for hangarage at Enstone Flying Club, though i'm not sure if they have much room. There is also a farm strip called Drayton St. Leonards just South-East of Abingdon, and I think they have hangarage. Finally, Bicester gliding club have hangarage available in the old RAF hangars at the airfield.
Hope this helps!
Ox