You should be able to bring food on the plane. You can't bring it into the country. When I was still eating gluten, I had bought a sandwich in England, and had half of it still in my bag. A cute little dog sniffed it out, and my bag was searched. The woman saw it was just a sandwich of cooked meat, and didn't make a fuss. I was very embarrassed, but it was okay.
You can't bring fruit from overseas here, or from the U.S. to England. But, I always bring a couple of pieces for on the plane.
Hope this helps.
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