u/Wonderful_Winter_363

I've been watching countless hours of content on this setting and people painting these models. I've ventured onto the zombie smith website and wargames Atlantic looking for the rule books and to put matters short, I dont know which rule books are necessary and/or up to date. I want to experience all aspects of this game including tractors and elite units. Do I need them all? Are they all up to date? I hope the veterans of this community can help me out!