Coeliac disease is when gluten causes damage to the intestines.
I happen to have intestines damaged by C-Difficile (was hospitalised in 1980) which resulted from prescription of a (now banned) antibiotic.
Because of decades of frequent diarrheoa I once paid for my own coeliac test
Biotech Biocard Celiac Test - Boots
..which showed negative.
I have learned what not to eat, and take vit/mineral supplements to compensate for my intestines' low capacity to absorb nutrients from food.
I do not expect the NHS to subsidise my food - even though I have this condition due to medical negligence.
PS I have never suggested that you pay for your own oxygen. I did note that you blame your poor health on decades of smoking.