In answer to Ray: The Canal du Midi has footpaths along one (or both) sides, well used by both walkers and cyclists. We've walked several stretches of it - and it's very relaxing walking - obviously flat for the most part (though not through the nine locks at Fonserannes in Beziers), plenty of birdsong and wildlife, lots of beautiful wild flowers all along some parts, not much noise except the chugging of boats, and usually quite shady. Lots of the locks are still operated by lock-keepers, and there are plenty of little houses along the way, some beautiful bridges, and plenty of villages to refuel!
We did come across one section near Capestang where the beautiful plane trees, which give the shade, had some sort of fungal disease, which had killed them, and necessitated them being labelled, felled, and the wood disposed of elsewhere - what a scar! I don't know whether they'll be replaced with mature trees or not.
We've been back thirty-odd days, and we're off again in less than thirty! As you say, I can't wait!