We live in Nantes and have homeschooled our two daughters several times. I would be happy to answer some of your questions about homeschooling in Nantes. It might be easier through private mail (but I don't mind on the list anyway). Our daughters (who are now 15 1/2 and 13) have been homeschooled in 2007-2008, for more than a year, and then our youngest, last year for 7 months. For some reasons, we have never been inspected by the Inspection Academique. There is a very nice group of homeschooling families, who meet very often, for different activities and leisure.
Let me know if you want to talk more about all this. I'd be happy to help, and to introduce you to families who are homeschooling now. Bye for now.