We were there in June. We had a difficult time getting food for the kids but we did manage to get meals there. We did not research it ahead, though. (I did bring a boatload of snacks with me, just in case.) Wasn't the ideal way to do it, but we managed.
We ate at a Burger King near the entrance for lunch, and then for supper we ate at the Dr. Seuss circus tent place (cannot think of the name). The cafes we stopped at to inquire did have allergy books, but there was precious little our two kids could have at most of the cafes, until we got to the Dr. Seuss part. Then, they could only have a hot dog and chips; I think we also bought a bowl of fruit if I'm remembering correctly.
If just a peanut allergy, you might have much better success than we did. With that said, my kids enjoyed the Harry Potter/Universal park even more than Epcot -- we did not do Disney proper
. We did other Florida things -- and had a great time.
My DD says the HPotter stuff was her favorite of this trip. My DS loved the Jurassic Park part and also the Gatorland park. I enjoyed the beach