Posted: 18/01/2015 at 13:15
I live in France too, but not the same situation. Dordogne, on a belt of limestone that runs through the middle of it from left to right. Means topsoil is thin, poor and alkaline. Last winter was very wet, but usually it's like England but colder. Summer gets into late 20s early 30s with rain sometimes and thunderstorms, but still have to water as it's not enough. I live here all year round so easier for me than for you.
It can be hard finding plants that like hot and dry in summer and cold and wet, even snow in winter. Sorry I can't be of much help, the hardest thing for you is that you aren't there enough for the plants. But some plants do survive without much care here, aubretia, yellow allysum, iberis (the perennial one) http://www.perennials.com/plants/ceratostigma-plumbaginoides.html http://www.crocus.co.uk/plants/_/geranium-macrorrhizum-bevans-variety/classid.2840/