Yes sativa works in the Central but the hybrids around "70 sativa x 30 indica" works the best.
The jamaican pearl work well in france, as well as some strains like the Easy Sativa you precised, some early phénos of the SweetBlue can works too.
Generally, strains who are harvested around late october are good under the line of the "Loire", up to this line, the late september mid-october strains works better.
If that can help you, i'm in the north-west and i flower outdoor the jamaican pearl without any problems (about 10/15% loose in mold the crappy years)
this two last years we have beautiful weather till end october (30 degrees the 30 october) but 15 days more and we can have snow (or rain)
go here , choose ur city and u could have the climatology of a normal year http://fr.weather.com/weather/climatology/FRXX0055