I am doing something similar here in Orkney, north Scotland.
If you saw my post on the How do I get Motivated? forum, yesterday, you will know that I am a member of Couchsurfing and this has the potential to be used for the sort of working holiday you suggest.
We have had people here digging the garden, repairing bikes, learning wild foods, making fire, playing games, gathering peats, learning navigation, exploring the Stone Age sites, cooking meals and many other communal activities, where we learn from each other.
I am keen to develop this idea further, so please keep in touch, and I will watch this forum with great interest.
We got a lot of plans - to build an eco-house out of stone and turf, to plant more trees, develop the garden, repair more bicycles, create a community garden, to repair and recycle clothing, to repurpose all containers and packaging until we have Zero Waste, to teach cooking and food preparation, to spin and weave and dye, to become a centre where good ideas can be stored and shared to the world.
We will be visiting Ireland in September to visit the Celt centre and to learn more.
So, count me in!
Also, I recommend: http://www.justfortheloveofit.org/home