hi Swirly, welcome to type 1 diabetes.
We've done disney with diabetes more times than I can remember now. It's not all that horrible.

You'll do great. I know it seems so overwhelming now, but in a year you'll be such an old pro at it you will wonder why you worried.
We've never found any reason for a GAC - one year we asked for one to wait out of the sun, since we were there in July, and that was pretty useless. We tend to have a good touring plan which eliminates any waits for rides, even at the busiest times of year. We try to test before rides, though, we test right in the ride. Sometimes we will purposely pick a longer ride so that we can have some down time to bring up a marginal blood sugar. I am trying to remember but I think we've only had to pass on one ride and when we got to the front we told the CM that our son was having a low and we couldn't get on at the moment and they just gave us a FP for a return. so in hundreds of rides, I think I remember once it being an issue.
Pack two or three times as much stuff as you think you'll need. Test strips, batteries, insulin, glucose tabs
Be prepared to test twice as much as you do at home.
Get a
frio case for your insulin (unless your daughter is pumping by then, then we don't bring vials into the park).
Carry glucose tabs with you at all times
Carry glucagon with you at all times.
Have her wear a medic alert bracelet
Carry something like a granola bar or pb crackers / cheese crackers with you as well.
Unless you're using NPH, meal times shouldn't be a problem. Just don't expect to get seated exactly when you think you're getting seated - don't take insulin before you're in teh restaurant with your food in front of you.
Blood sugars will be crazy while you're on vacation. Restaurant foods do a number - they're high in fat and that gives you a delayed fat spike. the good thing is that all the walking you'll be doing will bring her blood sugars down and the fat spike at night will help with that.
Mickey bars are the ultimate bed time snack. Regular ice cream works well too. Same reason as above, lots of fat to counteract all the exercise induced lows.
Watch for adrenaline highs from the excitement. Treat those cautiously. They usually crash later.
Just plan ahead. Carry what you'll need. Don't assume you'll be able to get it there.
Oh and watch out for overly cold room fridges. They've been known to freeze insulin.