As a mom to three kids with nut allergies, the start of school is always a little stressful for me. At Meet the Teacher, I always make the teachers aware of their allergies and talk about how to help them at school. I like to also send a "Safe Snack Bag" to keep at school, just in case someone brings in a class snack for a birthday party, etc. so that my kids will have a treat they can eat :)
Even though we have lived with nut allergies for 6 years now, as the start of school approaches, I still remind my kids about how to avoid nuts at school. We even practice what to say if someone offers them food at school. so they'll know how to respond.
Here is a letter I also send to my kids' teachers with a list of safe nut free foods. It's helpful to have on hand to refer to through the year... You can find nut free lists online. I made mine from a list I found and mainly included snacks my kids like. So these are definitely not the only nut free snacks available :) You just have to double check labels :)
(This list is NOT gluten free, only nut free :) )