Richard, have you got your copy of Miam Miam Dodo for the GR 65 yet? If not then get it, or at least download the App and follow the link to "acces aux plans". It's a bit clunky but persist. Make a few bookings now. That will give you some confidence. We often got our host to book ahead for us, no problem (offered to pay for phone call). You will see from Miam that many of the chambre d'hôtes and gites have English listed but don't be frightened by French, people are really very helpful. As someone else said, lots of arm waiving and gestures, smiling and a sense of humour help.
As for food, when you book ask for "Demi pension", and you will get a very reasonably priced and usually delicious dinner, as well as a light French breakfast. In the very small villages and isolated gites there is no alternative. We always carry a bit of dried fruit and nuts as emergency rations but otherwise just stop whenever we come to a bakery or chacuterie and buy a few things for lunch. Miam Miam Dodo will tell you exactly what food is available and where - it is invaluable.