I think food allergies are a fact of life in Sunday School and church in general. We absolutely avoid peanuts, other allergies we work around by providing alternate treats or recipes (rice flour rather than wheat flour?). The food workshops are so popular that I would recommend doing whatever you need to include some. Foods that might cause life-threatening allergies should be kept out of the church altogether anyways if there are people with allergies(ie nuts and seafood). There are always people with allergies around - we have a number of adults with serious food allergies, mushrooms, chocolate, dairy products. We still have potluck dinners, but always try to have an allergy-free choice.