Wellesbourne, Wellesbourne and Wellesbourne! I'm a little biassed being based there of course.
The restaurant at Calais is very welcoming and does a good lunch
I'll second Calais, also Cherbourg, and if you want to remain local you could try the restaurant at Gamston.
I'd have to plug the Pilot's retreat at my home field of Sherburn. The all day breakfast of course, but a choice of home cooked mains for lunch with the Sunday roasts usually seeing the place full to the gunnels. Great choice of places to eat around the airfield if you fancy something else - ask at the flightdesk for recommendations, and to arrange a cab or lift as sadly not really in walking range. Paul
Thirded for The Apron at Gamston. It's the best restaurant I have found at a UK airfield. The sort of place I would go to eat even if I wasn't flying in there. Utterly fabulous food.
This is great, my visit list is growing daily - please keep the recommendations coming if you have personally visited there and can recommend the quality and convenience. Travel to/from is a particular point - on occasion, taxi costs can more than the fuel to get there!