MTB Holiday thoughts in `North/mid France

I've a vague idea for 7 days in France. (10 for 11 days away including ferry crossings)

I think we'd get the ferry Portsmouth to San Malo then have a trip through France. We need to be no more than a 6/7 hour drive from San Malo. A very Quick Look at a map, based on green bits (!) and it looks like Dijon or somewhere in the Dordogne might fit the bill, but clearly vey open to suggestions!

I'm not looking for a weeks guided holiday, indeed we'd want to see some sites so maybe somewhere that is good for maybe 4 rides.. Happy to put routes into the Garmin and self guide.

Any suggestions/advice very gratefully received 

TIA