If you manage you allergy in "real" life when there are no nut bans then you can manage it at school. There is no such thing as a safe place whether nuts have been banned or not. What about the other children who have life threatening allegies to products other than nuts, are we going to ban those as well?
From the anaphylaxis campaign website
Nut bans
"Some schools choose to enforce ?nut bans?, where it is forbidden for any pupil to bring the problem food to school. However, without wishing to undermine the good intentions of any school taking this approach, The Anaphylaxis Campaign believes there are several pitfalls in this approach. It would be impossible to provide an absolute nut-free guarantee so the danger is that allergic children may be led into a false sense of security. There is a strong case for arguing that food-allergic children will gain a better awareness of their allergies, and learn avoidance strategies, if they move in an environment where allergens may turn up unexpectedly."
At one secondary school pupils threw nuts at a girl with nut allergy to see how she reacted - swollen face, adrenaline, trip to hospital. Of course those with nut allergy are never safe at school, or anywhere else, but it is possible to reduce the risk.
If they are going to do this type of thing anyway I very much doubt they will take any notice of a nut ban are they!