This is a pretty good discussion of the sustainability component of it. I apologize up front for just posting the video connection and not much more. I am terrible at posting videos.
But here is more about the guy.
Dave Hamilton (author)
He has lived all over the UK and amongst other things has worked as a market trader in Camden Stables Market and in Anjuna India, a postman and a gardener in Oxford and a driver’s mate and factory worker in Northampton.
He later returned to education and whilst studying a BSc in Nutrition and Food Science at Oxford Brookes he began growing his own food. Realising there were still bills to and full self-sufficiency was very difficult he coined the term ‘Self-Sufficientish’ which later was adopted by the website he runs with his twin brother.
He now lives in Devon where he is following another of his passions, that of plants, by training to be a sustainable horticulturist at the Dutchy College run course at the Schumacher College in Dartington. Along with fellow students on the course Dave has started up a sustainable bee keeping group using methods championed by Phil Chandler.