The recipe looked terrible until I saw you were doing a 15 gallon batch.
I've never used flaked wheat in an EPA, but that doesn't mean you shouldn't. I have used small amounts of torrified wheat, but I wouldn't like to go over 1/2 lb for a 5 gallon batch.
I like the flaked barley, and have used up to 1 lb in a 5 gallon batch, but I think 1/2 - 3/4 lb per 5 gallons is better.
Personally, I would replace the Crystal 20 with Crystal 60 (preferably English) and possibly increase it to 1 1/2 lb. This would give you a deeper color, and a flavour profile more typical of an English Pale Ale
I'd change the 60 minute hop addition to half the weight of something like Northern Brewer with about twice the AA%, but that's because good Kent Goldings are difficult to find, and I like to keep them for late additions.