It'd be interesting to know exactly how allergic your son is to peanuts. Given that he carries an epipen then presumably he is suspected of anaphylaxis but if he's never had a serious reaction then it may not be as bad as that.
Also, has he ever considered hyposensitisation treatment?
But as always, get in touch with the CAA and get the word 'straight from the horse's mouth' as it were, like Ulster says, it'd be interesting to hear what they have to say on the matter!