If you want to spend time exploring France, then one of the best ways to do this is by volunteering at an organic farm. This is also known as WWOOF - World Wide Opportunities on Organic Farms. In short, the concept is that you help out small or large organic farms in exchange for room and board. You can join the website (http://www.wwoofinternational.org/), and find a farm that is best suited to your abilities. Many farms have special projects that volunteers are asked to complete. You will be working alone, with the farm owners or other volunteers during your stay.
This is a great opportunity to learn French and to see a different side of the country. You will be expected to get your hands dirty, but the experience alone will be worth it. You will have the chance to expand your language skills while staying with the host family or farmers. Plus, if you have ever wanted to see a particular part of France, then this is a great way to do it. You can explore the surrounding region on your days off with ease.
You can also try volunteering at a local hostel or with camps in an area of France that interest you. Reach out to organizations that pique your interest. For example, contact the governing body of the Cannes Film Festival to volunteer if you love the cinema. You may get the opportunity to work during the festival and see some of your favorite stars!