Can you really build a Grand Design when you've only got ú500 to start with? That's what Simon and Jasmine Dale had in the bank when they started to build their unique three bedroom family house high up in the hills of rural Pembrokeshire. This is their take on 21st century low-impact self-building, featuring foraged and recycled materials. Despite the budget, their house will be open plan, have underfloor heating, an inside flushing loo, and a set of greenhouses that wouldn't disgrace Kew Gardens. They are part of a pioneering, government-backed, sustainable village called Lammas, which has a fierce planning condition attached: in return for the right to build on open farmland, they must become self-sufficient on their seven acre plot in five years, or lose everything. It's a huge double challenge.