Mobile Broadband/WiFi in France

Allyns

I intend to spend several weeks in France this year and will need access to WiFi. I already have a mobile phone and data card which I use in UK but would like to purchase a data only card for use in France. I am aware of the numerous free WiFi hotspots throughout
the country but would like my own data source should I need it. Does anyone know if such data only cards can be purchased at Euro Tunnel in the UK as I would like to be obtain one before landing on French soil? If not, any ideas where to obtain such cards
in France?