While I'm not affected myself, I need to keep a GF household for coeliacs and I've found it really easy to be on SW as they don't really encourage that many gluten based foods outside of the HEB choice.
Are you going to a group? If not, it might be worth popping along to a group (there's a free join voucher in this week's Best magazine) even if just to grab the updated books. You'll get access to the website as well which has more info on GF choices.
But basically, it's fine to substitute a GF version for all free foods - including HEBs. Although they do list some specific ones that qualify as "true" HEBs in their own right, which include cereal, bread and wraps. There's also all the non-grain based choices such as cooked fruits, nuts, etc.
These are the ones I personally have, but there are plenty more options...
BFree GF multigrain wrap (1)
Genius GF brown bread (2 small slices)
GF porridge oats, any brand (35g)
Schar GF ciabatta roll (1, either white or brown)
Kelkin GF sourdough bread (1 slice)
Hope that helps!