Greetings Peter,
I can't answer your question with regard to the brands that you name BUT;
At every supermarket with a fuel pump (and there are zillions in France) they sell Gas. It comes in all shapes and sizes and they have butane and propane.(But they will only sell you propane for the 'van. Butane is for the home, apparently)
A couple of years ago I bought a Primagas gas bottle from the Auchan supermarket at Calais. Quite straightforward. I approached the kiosk and in my best schoolboy french asked for a bottle. The lady gave me the key to the cage and out came I with the bottle. I was given a receipt that included the price for bottle (refundable) and the gas.
I chose this particular gas because it is available throughout France with the added advantage that the pigtail on my post 2005 van was for the small butane calor bottle at home, and that pigtail fitted the outlet for the French bottle so there was no adaptations to make.
The only downside is that the bottle is approx 14kgs so you have to have the available noseweight, and, like the UK, the bottles can't be exchanged anywhere other than France but, because we go so regularly, that isn't a prob.
Anything else, just ask
Regards