I'm a coeliac, it came completely out of the blue as I didn't get the typical bowel symptoms. This is probably the most useful but of info you'll need.
From coeliac UK website:
‘A breadcrumb won’t hurt someone with coeliac disease’...myth
Even very small amounts of gluten can be damaging to people with coeliac disease. Therefore, taking sensible steps to avoid cross contamination with gluten is important.

Top tips include:
• keep cooking utensils separate during food preparation and cooking
• avoid frying food in the same oil that has previously been used to cook foods which contain gluten
• use a clean grill, separate toaster or toaster bags to make gluten-free toast
• use separate breadboards and wash surfaces thoroughly
• use separate condiments like jam, butter, mustard and mayonnaise.
Lots of foods are naturally GF and the range is improving all the time so it's not too bad but it's the cross contamination that makes it hard.
Gluten still damages the gut even if you don't get symptoms, so he 'lol need to be really careful.
In the early days I got glutened all the time by silly things you never think of. I shared a bowl of chips with a friend that was eating a sandwich and got ill from a tiny bits of gluten on her fingers touching the chips. Same happened with packets of crisps. DH and I now don't share drinks if he's been eating gluten.
Buffets are out unless you get first dibs, its a cross contamination nightmare.
Eating out is much easier these days and I rarely ill. You learn quite quickly who does & doesnt understand the contamination risk by asking a few questions.
I've found some friends really get it and I'll happily let them cater for me, others I know don't understand it, which is fine and I take my own food along. It's really easy to slip up in ten early days so we when totally GF for a bit but manage it no problem these days.