I've been Type 1 for 45 years and was diagnosed coeliac almost 8 years ago, at my first coeliac test at my annual review. I had no symptoms. I was referred to a gastroenterologist who gave me an endoscopy for the full coeliac diagnosis. When he gave me the result he said I should go gluten free. He also said that if I continued eating gluten, there were a "couple of nasty cancers" I could get.
Being gluten free is no real problem. Most food is naturally GF. "Normal" baked goods are ones you avoid. Even since my diagnosis, GF bread has improved greatly. Different people have different tastes, but I prefer Warburton 's brown seeded bread.
I avoid most GF biscuits, not because of diabetes, but because most of them are far too sweet.
My main supermarket is Asda. Their own sauces tend to be GF, but I check every time I buy one, as sometimes contents change.
Free From sections in supermarkets are where you find GF bread, pasta, gravy granules etc.
Unfortunately, the choice of GF prepared foods in shops isn't as good as it was, especially in Marks and Spencer, but I'm sure you'll find an adequate supply, even if you need to shop around.
Dining out can be a problem, especially for lunch. A full meal is easier to find than a sandwich. Be careful eating out, and double check that the meal/bread brought to you is GF. Sometimes mistakes are made (even in a nearby NHS hotel adjoining a hospital!)
You do get used to being GF, but it can be frustrating at times. However things have improved in cafes/restaurants in recent years.
Good luck!