At MK -
Rays Starlight café - is our favorite - they have 3 bays with different items on them, and have a burger topping bar which is great. We love eating here. Lots and Lots of good memories, and new ones to be made. Food is pretty good, burgers, hot dogs fries- Chicken plate is really good and I think can easily be split between and adult and small child.
CR - quick service option they have really good sandwiches,
Poly - has Captain Hooks - and if I remember right they have a pretty good bbq sandwich.
If you are heading over to DTD - Earl of sandwich is the best and very reasonably priced.