I don't know what luxury level you are looking for, but you could always start with Gites de France and Clévacances, reliable agencies. Also you could decide on a town/village and then contact the tourist office or town hall (Mairie) for information as they usually maintain accommodation lists for their patch, together with contact details.

For guidance as to where, we could do with more details such as whether you want to live in a village/town, in remote areas, up a mountain (not a joke) whether you want/need a pool, and whether you will be independently mobile (wheels not your state of health!). It also depends on when you want to come ... you've probably left it too late for this summer!