http://www.amazon.co.uk/The-Eating-thro ... B00NPCEW9A
It's actually really well thought out, and applicable in non-zombie related situations too. It has foraging guides (although bear in mind it's an American book so some of it won't carry over) but also guides to cooking, making things like ammo can ovens or hobo stoves, and recipes based around the sort of stuff you'll be able to get hold of.
Plus some handy tips on things like gauging temperatures for cooking and practical things like making snares and various traps.
It's also quite amusing, which helps