Try "cruising French waterways" by Hugh McKnight available to order from your local bookshop ISBN No:0-7136-5005-2
This will give you an insight to various routes and the legal requirments (cevni rules etc
If you are thinking of going soon,the canals are shut for approx 6 wks from beginning of Nov: Details from VNF (Voies navigables de France)++0033 326857595
Just to chip in with some 'local' knowledge, it might be useful to remember that the Canal St-Martin, which cuts through Paris, has now been drained and is undergoing major works. So, forget cruising through the capital for a year or so!
Feb -March is flood season on the rivers,best avoided.Certain canals run out of water near summit(Bourgogne?)Try the afore-mentioned book, also Marion Martin has written a couple of books.Don't forget,if your a yotty type,your mast will have to be un-stepped and places that can do this are listed in these books.