British Expats - mobile internet

I know this has been discussed before, but it's an ever changing market so someone may have more up to date advice than I can find.

In March we plan to put our boat back in the water in Le Grau d'Agde and start up the Canal du Midi, slowly cruising and house hunting. Previously we have used an Orange sim for mobile internet and got around 8gb for 20 euro per month (I think), renewable by phone with a top up ticket from a tabac.

In 2013 I discovered a fantastic deal from a French company called Joemobile set up for expats because you could use a UK bank account to set up a direct debit and got around 14gb for less than the Orange deal. This lasted 1 month for me before Joemobile was bought out by Virgin who then wouldn't accept a UK direct debit so I lost the good deal. I finally got a deal through a friendly mobile shop guy who set an account up for me using the marina in St Mandrier sur Mer as an address then paid the fees for me and I paid him cash in advance. This got me a good deal, but I can't rely on finding someone so helpful again.

Roaming charges have gone, but UK mobile companies have fair usage clauses and even know when you tether your phone to your computer. We would undoubtedly fall foul of both of them.

Has anyone found any particularly good mobile wifi deals? With luck we will have sorted out a Britline account for the short term before we arrive, giving us a direct debit and can use a marina as an address, but may have to go back to a payg data sim.

All advice gratefully accepted as usual.