Main points seem to have been covered, so just to reiterate, it's a PAIN IN THE TITS.
For shop-bought bread, Genius brown and seeded are pretty decent- the seeded reminds me of old Mighty White. Glutafin Select multipurpose white mix makes a decent white loaf- if you're going to do your own, get a bread machine, it'll eat too much of your life otherwise.
For riding- the mighty rice crispie square is gluten free. There's various bar options- 9bar, nakd- but I've not found one i like. There's a gluten-free oat bar that Tesco sometimes have which is passable.
The Genius pizzas are OK if you like thincrust. The DS ones that Asda sell (sometimes also tesco but only Asda seem to carry the pepperoni ones) are better though.
And for pasta, Doves Farm is IMO the only one to use- there's plenty of others that are decent, but it's almost indistinguishable from real pasta (it goes a bit slimy when it cools, is all)
Lastly, eating out... Call ahead, ask the questions, don't be afraid to be a pain in the arse. Watch out though, I've had such highlights as a chinese place serving me a meal I couldn't eat because when I said "gluten free", they had no idea what I meant so assumed I must mean "MSG free". Grr.
Oh and last comment- ask about followups for anaemia and osteoperosis. Cyclists are predisposed to osteoperosis anyway- we sweat out a lot of calcium and it's a fairly lowimpact sport- but if you've been affected by coeliac for a while you could be pretty calcium deficient. THere's treatments for this and it's better to find out now, than by falling off and breaking all your s**t.
Good luck!