One of the best breeds for free-foraging (albeit quite rare) is the Manx Rumpie. They're a rumpless Iranian breed, very good layers, and quite hardy. You might want to look into them! My two Manx Rumpie mixes are excellent layers and the man I got them from was telling me about how hardy they were bred to be. The only thing (other than the fact that they're hard to find) is that fertility is not good on them so they are difficult to breed. Anyway, just thought I'd bring them up. They're awesome birds and worth looking in to.