Really need some advice about travelling throughout Southern France - car, bus or train?

Ok, so I booked a return flight to Bordeaux on the 28th September and was due to come back to the UK on 5th October, but now I can extend my stay until about the 16th October as an appointment I had in England has now been cancelled. I intend to visit Bordeaux, Bergerac, (maybe Carcassonne), Perpignan,... show more Ok, so I booked a return flight to Bordeaux on the 28th September and was due to come back to the UK on 5th October, but now I can extend my stay until about the 16th October as an appointment I had in England has now been cancelled.
I intend to visit Bordeaux, Bergerac, (maybe Carcassonne), Perpignan, Montpellier, Avignon and finally Marseille.
I found this website called wheretosleep where you can book reasonably priced rooms in villas and homes throughout France (and the world I guess) but some of these accommodations are about 20km from the place I actually want to see (e.g Bergerac).

When I last travelled to France two weeks ago (Paris) it seemed to me that there is no coach service there - like National Express? Only trains which are quite expensive in France. I cannot hire a car as I paid off all my credit cards last November and effectively got rid of them. I only have a debit card which I presume you cannot use to hire cars.
So my choices are: trains (expensive), take my own car (uploading French maps to my satellite navigation system but I am worried about driving in France - on the right and all that - Never done so before).

If you were me, what would you do? Drive to France with your own car? Fly there and take public transport or see if there is a car hire service that takes debit cards? Incidentally, is there a coach service in France?
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