I find that Waitrose/Ocado have by far the best choice in gluten and dairy-free groceries. If you look at the Tesco ingredients they often include whey powder etc. I have Rude Health rice cereal, chopped banana and almond milk (light) for brek, millet bread and almond nut butter (toasted) or home made soup for lunch, or sometimes microwaveable Puy lentils and fish/salad. Or sweet potato, lamb, chicken, turkey. Buckwheat pasta is good, rice noodles too. Avoid oats as they do have gluten most of the time, unless you buy specifically gluten-free ones, same with spelt, rye and barley. Quinoa crackers are good. Shop in the wholefood or health food shop too, as most stuff in there is good.