@PeachesPumpkin - please don't think I'm making light of coeliac disease. I'm not. I know two people who are having to navigate it and I know how ill mistakes make them. But by calling anyone without it a 'Muggle', you are mocking everyone else and that won't help people want to understand.
I want to gently point out that many of the challenges you are explaining do not apply only to people with coeliac disease.
A lot of what you said applies to me. I have ulcerative colitis and a heightened risk of bowel cancer. I have a mild allergy that wasn't pinpointed until I was in my 20s but had already damaged my digestive system. If I eat that allergen by mistake in any great quantity it can trigger a flare.
I can't have a 'cheat day' with at least 2 groups of my allergens because with 1 of them I would almost definitely die straight away and with the other group I'd be very unwell.
Try imagining what it is like to be Coeliac. So much of socialising is around food.
I can't eat out at many many restaurants so have missed out on social events organised by people who aren't close friends when they've been held somewhere that I can't go (for example my previous employers weekly staff lunch was at a Thai restaurant - a complete no go for me even just to sit and have a drink) and with my good friends I have to be the awkward one who they have to plan the restaurant around.
I do manage to eat at friends' houses as they are so so careful and go to great lengths not to cross-contaminate (and they don't cook with my allergens at all the day that I'm coming there). Before I eat at a friend's house for the first time I have to send them my list of allergens. It's excruciatingly embarrassing. It's a list of around 30 food items.
I can't even be in the same room as some of my allergens so have had to walk out of parties the minute I've arrived if bowls of nuts are out.
And back to where this thread started, buying a loaf of bread. Well, there is one loaf of sliced bread that I can buy in a shop. It's made by a non-uk producer and can only be found in some branches of Waitrose. I'm pretty sure that I'd find it easier to get hold of a gluten free loaf than a loaf that doesn't contain stuff I can't eat.
I've got used to dealing with all this but yes, it's wearing and a bit pants.
I'm trying to explain that lots of people are dealing with medical issues that impact their daily life. There is no medical condition top trumps.