For expanding your vocabulary, I'd recommend you read some books that are at a light reading level. I myself, while I love to read, have a hard time doing it. So I figure books that I find easy might work out just right for you.

With that in mind, John Steinbeck would probably be a great place to start. His novels in and of themselves are fairly easy to read and he doesn't use too many words that'll make you scramble for a dictionary every other paragraph.

Pulp novels, like the John Carter Series by Edgar Rice Boroughs, while science fiction, are also easy to read through. Plus, they're good old fashioned fun.

As for expanding your grasp of the spoken language, don't judge me here or think I'm insulting you, but I'd really recommend you watch cartoons. Because they're created with children first in mind, they tend to use simplified vocabularies. At the same time, they're often colorful enough to keep your attention even when you can't understand everything that is being said. This is the perfect time to watch them as well, because even though they're meant for children, a lot of adults watch them too, so a lot of the stories don't shy away from higher concepts. I don't know if France has Netflix, let alone shows American cartoons, but if it does, that's a great place to start.