Love the sound of what you do and what you are looking for!
We (family of 3, daughter 14yrs) live in southern Catalunya. We only have a smallish plot 1250 square metres with a off grid cabin that we live in, we are planning to turn the land into a food forest. Would you be interested in this area? There's a few British people living in the mountains around here with lots and lots of land and most don't even know what to do with all the land. If your interested i will give you some pages to try I'm sure you will get a result.
Your welcome to stay here anytime if you decide to come over and check places out etc we have a small caravan on our land.
Hope you find your dream place soon