With plenty of marinas, most with adequate wifi service, and thorough mobile phone coverage at reasonable rates, Internet weather maps have become accessible and affordable, especially as roaming rates have been capped. Mailsail and Saildocs grib filesremain the cheapest and (once set up) the easiest and most reliable.
Additionally there are excellent local services. Both the French and Irish vhf weather forecasts are excellent, and give much more ‘Actual’ data than in the UK. Both also give swell heights, which the UK does not.
In France, there is also the daily half-page of weather in the Ouest France newspaper. Throughout Brittany, the Vendee and Charente Maritime, this paper is available daily, including Sunday. It seems the French have a greater obsession with the weather than the British.
Reading this page and listening to the French VHF forecast, one quickly acclimatises to the French terms used. The dictionaries in Bloc Marine French/English almanac are also most helpful.
Scanning these maps into a Log adds colour, and can be informative. The only snag is that you have to keep the papers till you get home and can scan them into the computer.
It is probably easier to rely on weather sources with which you are familiar, but national services are worth a look. I have used these services in ireland, France and Norway (when we went up the coast in the ferry).
For looking a week or two ahead, there is little to beat the European Centre for Medium Range Forecasting (ECMWF)