I can also vouch for Chocks Away, nice food, good prices, & you get to see whats happening on the runway. Also has good outside seating area.
Another good one is the Lock Lounge Cafe at Sleap airfield - much the same as Chocks Away regarding price & viewing facilities, but also serves a fantastic Sunday lunch as well as a varied menu.
Going back a few years, wasn't there also a pub called 'The Airport', right off the runway at Manchester, where you could have a bite whilst watching the aeroplanes?