I think it has always been a legal requirement in France (as anywhere else) to provide an address in France. It’s a basic anti-fraud measure and they are very strong on that here…
I remember my first French mobile about 15 or more years ago when I used to fly on a regular basis to France and obtained a PAYG from Orange. Didn’t need a bank account but did need an address. I used a friends address (with his permission) for this purpose.
It wasn’t ideal; the PAYG contract required prepayment credit which if not used by a certain date would simply be lost but you can obtain credit facilities from buraliste and supermarkets.
In order to obtain a bank account without the usual expense, consider one of the on-line accounts freely available these days. I believe they allow you to use your UK address and will likely satisfy French mobile vendor requirements.
How do you pay your taxe foncière? surely there is an address for the land which you can use?