It should be possible for other CCGs to liaise with them to learn from their experiences.
As for availability of gf foods - staples may remain in larger supermarkets, but if the demand by non-coeliacs for gf were to decrease I would doubt that smaller stores will offer much of a selection. If a product does not sell enough, if there is insufficient 'churn' on a supermarket's shelf, then hard economic reality hits, and products are considered for delisting.
We have seen what happens when demand for a certain sector rises and then declines - just look at the organic sector. Yes, I can buy organic milk in my local (smaller branch) Waitrose, but cannot always find it in my 'local' Tesco or Sainsbury; other local convenience stores used to offer organic milk, but now they do not.....
Not everyone lives in an urban location, those in rural areas will find it more difficult. Pharmacies are located nationwide, so perhaps some scheme which includes the role of the Pharmacist and Pharmacy would be appropriate?