I can relate, my son is allergic to nuts, eggs, milk, peanut & a variety of animals. And I was SO worried about his allergies in school. To the point I considered home schooling, just to keep him safe.
But, in the end I decided pre-k was best for him. And I found a great private nursery school with two fantastic teachers. (it doesnt cost as much as your may think) And they take his allergies very seriously.
He has an epi-pen in his backpack AND in the classroom. Whenever they go outside, the teacher brings Joey's backpack with her. And I have popped in on more than one occasion to see the teacher wearing his backpack.
The beginning of the school year I make a batch of his cupcakes and freeze them in ziploc bags. They sit in the freezer, and when another student brings in an unknown snack, or has a birthday ... My son has cupcakes of his own, and he isnt left out.
We have taught him to always ask if something has peanuts in it (thats his biggest allergy) before he accepts anything. He also will ask if foods will make him itchy or sick. He even asks me that question when I give him something new. :)
Prek has a been a wonderful experience for him. He loves going. He has made a ton of friends. He knew his letters, colors, numbers, etc before going. Pre-k, for him, was more about being independent and social.
I have checked out other schools. And I did not feel confident in their ability to monitor the safety of my son when it comes to his allergies. The best thing to do is check out as many places as you can, and go with your instincts.