You should be able to get complete ferret food from pet shops, or from animal feed suppliers. If not, look online, may be able to bulk order a load.
I personally feed on carcass as much as possible. During the summer, mostly they have pigeons that we've shot, or mates and mates of mates have shot, during the winter, when its ferreting season, they'll get mostly rabbits. I'll pick up road kill partridges or pheasants often, and I have a few shooting mates that get me the odd squirrel, crow or magpie. Recently they've had goose that my mate only breasted.
I'm not a fan of dried food,