I've tried FODMAP too, quite restrictive and didn't work for me but has good reviews! Serious label reading is key though as the things to avoid are in all sorts!
I'm sure you can get gluten free oats, special ones, I'm sure I've seen the in Tesco's with the gluten free stuff. This company do a lot but they aren't cheap, they have the bread in Tesco (as well as Genius).
http://www.newburnbakehouse.com/supermarket-products
The Blue Cheese Flavour Cracker Thins look nice!
Genius here:
http://www.geniusglutenfree.com/en_GB/?site=geniusfoods&clear=true
The gluten free bread really isn't great and stupidly expensive. I saw something on Facebook the other day of someone making a "brown bread" out of mainly oats and yoghurt, might be worth looking into. Looked much quicker than making normal bread.
If you check some coeliac sites, they are likely to have ideas and recipes for gluten free and it seems to have become much more common these days so there are special cookbooks about. Pharmacists might have an idea of the best products to buy as people with Coeliac and can get some items on prescription.
Oat cakes and rice cakes can be quite dry and a bit bland so good to have something to go with them.