Hello Le Hibou. I live in Dordogne. Before coming here I lived in Kent and had a lovely garden which I'd opened to the public for leukemia research and I used to enter the village flower shows. I've been in this house since 1990. There wasn't a garden, lots of brambles, nettles rough grass and weeds on shallow soil on limestone with clay pockets. The weather is as you describe! I have made a flower garden and a vegetable garden. Part of the garden is in my identity photo. Although there are many plants that I've lost because of conditions here, many more have survived.
I find plants flower earlier here and don't last as long as in England because the heat in July and August can be too much. Annuals in pots do very well, but I water them a lot. Onions, tomatoes, courgettes and squash do very well. The runner beans were fantastic this year, but some years I don't get many in Summer but if there is warmth and rain in autumn I get an autumn crop. I think the lawn suffers most, grass is nothing like the soft green stuff in England.
I have horses so I have plenty of manure. The soil was alkali 9 at first, now it's much more managable and about 7. It was so stony and thin except for the bits you could make bricks with.
Now I've bored everyone too.