Well, looks like everything is booked anyway. Can't get a reservation for lunch anywhere at MK for that day. So ... hopefully, there will be a McDonalds there! Our trip is very last minute and I had no idea we'd need to make reservations ... and there wouldn't be room for us two weeks ahead. If we ever make it back, I'll know how this stuff works.
There are plenty of CS places to eat at the MK if you can't get an ADR. There aren't any characters at them but the food is good:
Cosmic Rays
Pinocchio Village Haus
Casey's Corner
Columbia Harbour House
Pecos Bills
Good Luck!!!
Bucky is absolutely right - there are many great counter service (CS) options available inside MK.
But the others are also right that there are several excellent table service (TS) options at the monorail resorts, and at Wilderness Lodge and the Ft. Wilderness Campground, which are only a short boat ride from MK.
If you can't get an ADR at any of the in-park places, try for an ADR at Concourse Steakhouse in the Contemporary, or Kona Cafe in the Polynesian. They're fairly popular places, but I think you have a better shot at getting into them for lunch than for dinner, because the majority of folks are in the parks in the middle of the day.
Failing those, try for the Whispering Canyon Cafe in the Wilderness Lodge. The lobby alone is worth the boat ride to WL, but WCC is a popular place.
And if al else fails, go to the Trails End Buffeteria at the Ft Wilderness Campground (the boat to WL also stops at FW - they are next to each other on Bay Lake). Trails End is the best-kept secret at WDW; it's a simple, down-home style buffet with excellent quality food, and is the cheapest buffet at WDW.
The boat ride to either WL or FW is a terrific, relaxing experience through beautiful scenery, too.