Hi Philippe,
Great that you are planning to try to live in Portugal, we need more like minded people to occupy our rural areas, to live a more sustainable way of living.
Perhaps, you can find a few examples of projects here on this network, depending of the location that you are aiming for.
http://www.redeconvergir.net/
Here you can find a FB group, which you will find people trying to help.
https://www.facebook.com/groups/pureportugalgoodlife/?fref=ts
You are more than welcome to make a visit to the reforestation project that I´m collaborating and starting my own permaculture project.
https://ecosanto.wordpress.com/
All the best of luck!
Take Care
Jorge