How old is she? Maybe I missed that in your post.
I don't have a child with allergies, thank God. I am however a long time substitute teacher, 15 years, and at our school it is imperative that the Childs home room teacher and nurse are aware of allergies. We have lists in the classroom and grade levels if allergies so we know what's going on and with whom.
The nurse has any prescribed RX and if needed to be on the safe side due to the severity of allergies, an Epi-Pen in in the classroom as well.
We also help children with allergies and encourage parental help in educating them on food choices, what their allergies are , etc so they are knowledgable, aware and know what's going on in their bodies if they happen to ingest something that someone might have missed along the way. It's so important for your child to be a proactive part of this process so she/he has control vs everyone micromanaging what he or she is eating.
We have 100+ children per grade level in K-5. We can't manage what each kid eats 100% if the time but we do have a "watch list" we follow.
Our cafeteria has a couple of tables set aside for allergy tables.. No nuts, etc.
Most children with allergies do bring lunch and sit at the special tables with a friend. The cafeteria also posts all ingredients online.
On days when parents bring in treats for birthdays.... We do not give anything to any child that has a label or that we are unsure of. Each teacher has a stash of " approved" foods from parents that are special treats on those days.
Hope this helps!! It has helped a lot in our schools. Empower the child with knowledge to take charge for themselves.