In reply to laurafennelly:
I've driven there a few times. I have a van that is just high enough that it usually gets charged at a higher toll rate too so by and large I avoid the peage.
What I've taken to doing in the last few years, particularly for France, is having a play with the route options beforehand on google maps and a toll calculator website. You can see which sections are the most expensive in terms of tolls and you can see which sections save the most time and decide on a few bits of toll road to use to save time in the most economic way. Luckily there aren't really any mountains between Calais and the Verdon so even avoiding the peage the whole way doesn't add too too much extra time. I'd recommend avoiding the peage at least as far as Dijon as it's pretty quick roads up to there.
Also, you can advertise your free seats on UKC and get a bit of fuel/toll contribution that way too.
It's worth thinking about how your time stacks up. Including the ferry and driving in the UK it is fully 2 days of driving to get to the Verdon and 2 days to get back. If you are going for a month that's fine but if you were going for a week it would just be silly. If you fly and hire a car, you could feasibly spend only half a day in each direction. I don't know enough about the trains to comment.
I would say that you _can_ do the Verdon without a car and just take a backpack but it would be very limiting because there are many good sectors that are too spread out to walk to and just going down to the village shop to stock up on supplies would become a bit of a mission.