I know how you feel; I had my parents buy some food for dinner from a supermarket whilst we were away which contained wheat when they assumed that it did not. I think that this showed to them exactly how hard it was for me to avoid wheat when I looked at the chinese ribs (dismissed them out of hand; shop brought chinese stuff is almost guarenteed to contain wheat thanks to soy sauce), sauages (again, dismissed out of hand due to rusk) and processed turkey rasher things (damn maltodextrin). Ended up going back to the supermarket to pick up plain chicken and a few other bits and pieces.

Personally I'd use the word "allergic" rather than "intolerant" as it would appear that people pay more attention if you say that you're allergic to something rather than intolerant.

I'd be happy to cook food for you if you like.