I can recommend two excellent (and affordable) food pubs within 5 minutes by taxi from Cranfield - either the Swan in Salford, or the Carrington Arms in Aynho. (Various okay but less spectacular eateries on the airfield - the most enjoyably quirky of the bunch probably being the Cafe Bookshop).
Generally speaking, eating on the grass outside at White Waltham is also a pleasurable experience. I'd say the food is Good rather than Excellent.
Denham has a rather good if quirky place on the airfield called Biggles :
Biggles Restaurant, Denham
A favourite of mine, also at Denham, is "The Crew Room", basically just an airfield cafe run by a fellow who used to have a larger Italian restaurant. His freshly made pizzas are quite spectacular.
I've not been there for a while, and recall it as more "good" than "excellent" (possibly "okay"), but the place at Lydd serves all day as well.
Restaurant & Bar - Lydd Airport (London Ashford Airport)
Red Lion is very nice for food, 10 minutes walk from Halfpenny Green.
Another I've not been to for a while, but the Crab and Lobster, 10ish minutes walk from Bembridge.
G