Hello, Judy!
You are going to have a wonderful trip to Walt Disney World with your granddaughter! How exciting!
We've traveled with family members and friends who have a variety of special dietary needs, and we've always found that Disney is so very accommodating to Guests' requests. First, check out the
Guest Services / Special Dietary Requests page on the Walt Disney World website, where you'll information regarding food choices while dining at Walt Disney World. Should you have any Table-Service reservations, as your server to speak with the chef, who will be thrilled to come to your table to discuss dietary concerns and customized options for your granddaughter. This has happened countless times on our trips to WDW, and it seems as if the chefs are eager to create a delicious meal which can be enjoyed by any Guest, no matter what the dietary concern.
Another source of information can be found at one of my favorite unofficial sites, allears.net. Once at that site, hover over "Walt Disney World" and click "Dining." On the left side of that page, scroll down "Special Dietary Needs" where you'll find even more information and reviews about dining in Walt Disney World while going gluten-free. It's a great source of information, and I think reading it will bring you confidence as you head into the parks with your granddaughter.
Have a fantastic trip! Be sure to send more questions as you think of them! I love to help!