I am coeliac and am on a gluten free diet. This means no grain atl all except corn. Even cornflaks contain gluen in the form of barley malt. Check the labels. Most supermarkets have free from displays. Otherwise you will have to learn which foods contain no gluten/wheat. My faves are nuts and fruit, rice, milk products, eggs, meat, fish, veg. Also there are loads of gluten free products with no wheat in them. Coeliac.cu.uk have a booklet which they give to members listinf all the gluten free products like wheat free bread. They may send you one if you say you are thnking of becoming a member.
I get my products free prescription cos I am over 60. Otherwise they are quite expensive. You might have to stop eating bread, paster, pizza, etc.
As for yeast. All alcohol contains yeast. But not all contain wheat. Beer is out. Cider is in. Wine is in. All spirits are in because the gluten is distilled out of them.
Hope this helps