Hi Bill (Greet) welcome to the forum, hope you and your wife enjoy your holiday in Calis.
I'm Coeliac and live here full time, you can get some biscuits ( a bit like chocolate rusks) and small chocolate cupcakes in Kipa, (Tesco) the brand is called Pronot. Unfortunately you won't get much else. Eating out won't be a problem if you avoid sauces, although most here are made with cream or tomato and oil based. Most products which use wheat starch in the UK use corn (miser) starch here. Do be careful with some of the rice it is made with little brown grains in it, these are a type of pasta made from wheat.
I believe that Bostons can do you a gluten free meal as one of the owners suffers from a wheat allergy. Also Barbella do some gluten free cakes.