Beginning of Gluten Free Lifestyle

My son is Autistic and we have just began the gfcf diet. It’s been 2 1/2 weeks and so far we are doing OK.I can see that it will get harder as we go on. Once he will eat more food. What I’m struggling with at this point is the hidden gluten and casein in packaged foods. If any of you know of a site or a list I can found of acceptable foods that would be great. I have an unacceptable list. I’m looking for things I can buy in a regular supermarket. I came from a very small town. The nearest health food store is 40 miles away. (and it’s not a very good one.) I would appreciate any help I could get. It’s nice to know that there are 1000’s of us out there trying to accomplish the same goal.