We are unpacking the disaster to travel that is Brexit. It seems that to travel to our place in France we will need all sorts of documentation (but not a visa), such as an 'attestation d'habitation' which proves that we have a place to stay.
So this morning I contacted the maire, and within an hour I got a reply from the delightfully named Fanny Hénault, telling me what I needed, and how to get it - followed up by two further emails gicing more details (I need to supply a photocopy of a utility bill by post).
Cracking service. A local mairie for local people.