Leaving your boat for the winter
Leaving your boat in France for the winter is not as expensive as in Britain. There are more facilities for leaving a boat in the south of France, than in the north. Most of the long-term mooring facilities are in Burgundy and along the Canal du Midi. France is a perfectly safe place in which to live and leave your boat as the levels of delinquency, vandalism and street crime, with some exceptions, are a long way behind Britain and most boat yards have good security.
All ports of entry into the canal system have long-term mooring facilities but these tend to be more crowded and more expensive than the facilities inland.
There is also a mooring place in the heart of Paris - the Arsenal. But it is expensive.
You will find marinas marked on your Navicarte/Fluviacarte or similar and most will have over-wintering facilities but do contact them ahead of time to reserve your place. The Carte Guides tend not to be updated very regularly which is why the Cruising Association now produces Cruising the Inland Waterways of France. You will find much more recent information in this document. A list of recommended over-wintering places is available to members of the Cruising Association as a download from the website.