I have just been on one of Patrick Whitefields course so kinda know what it is
Permaculture is most about sustainability and how to use the land to it's best without detroying its natural diversity or fertility. Most people grow Mono crops - but with this method the soil (the most important factor of gardening or agriculture) is left bare to the elements thus leading to loosing nutrients and in extreme cases desertifaction. Hence most permaculturist use a no dig system. The most important nutrients that live in the soil only go about 3 inches down if they are torn apart moved deeper or exposed they will die, so using mulch that will rot to clear the ground and planting a good cover crop eg white clover or a mixture of plants for example the 3 sisters corn , beans, and squash the squash helps protect the soil br keeping it covered, the beans fix nitrogen in the soil and the beans also climb up the corn.
Basically it is a design system that makes sustainabilty and diversity the basis of it's structure.
As another example are Permaculture Chickens. If you look at battery hens they are hard work , poorly looked after and use a magnitude of resourses to keep them alive . The barns need huge amounts of Electricity to run the heating and the cooling systems as well venitilation as the noxious fumes are unimaginable, then there is the use of pesticides,hormones and antibiotics that the chickens need just to stay alive. And you only get a single result EGGs. Where as a permaculture chicken uses and needs a lot less resourses. You can grow crops for chickens to eat, or let them into a nearby wheatfield after harvesting to find left over grains (great if you want to grow something else the year after) or in an orchard to keep down pests and weeds. If you link their coop to the greenhouse they will help keep it warm at night, so their is less need for a gas or oil heater. Feathers can be used for pillows eggs for brekkie and if you want eat the chicken, as you can see rather a lot of uses for just a few chickens.
Sorry rambling now.
I think the best place to start Is Permaculture in a nutshell (describes the chicken in a lot more detail) and go on from there. Gaia's Garden is another really good book. Then if permaculture takes hold Bill mollisons books are good and The earth Care manual is fantastic and deals with Britains Climate, although the way things are going I doubt we will be temperate for much Longer.
Carlie