Hi, I am also Coeliac and live in Spain, I find eating here is really easy, Mercadona supermarkets label everything that is gluten free "Sin Gluten", this is a little emblem on the front of packaging in red & blue. Mercadona also do some speciality gluten free products this may vary by store but my local one does mainly Procelli brand of Bread mix, part cooked baguetts, loaves of part cooked bread, magdalena cakes which are like fairy cakes, croissants, they also do Dietary supplies cornflakes and coco puffs and I can get 2 types of biscuits, La Galleta Maria and cookie con chocolate, the brand of these is Hacendado
Most packaged meat, ie mince meat, burgers, sausages etc are also gluten free as the Spanish don´t seem to add things to their meat products, again look for the sin gluten emblem.
If you go to yr dietetica shop in town and ask for sin gluten, you should find they are able to supply you with lots more items like pizza bases, breadsticks, melba toast, more biscuits, breads, pastas etc, my local shop gives me their booklet, I tell them what I want and its usually in the shop 2-3 days later.
If you need any more information please let me know :)