I like the food at Compton Abbas and Old Buckenham. A nice mixture of all day breakfast, nice burgers & salad (and chips), freshly cooked omelettes and salad plus Lasagne and salad and a few other daily specials.
I don't know if you've visited either of these airfields but they attract as many aviation enthusiasts by car as they do by air and always seem busy. This must mean that the restaurant has some customers when the weather isn't great for flying.
Nice toilets and pleasant surroundings also make a difference.