New to Trench Crusade

Hello everyone,

1 week ago learned about Trench Crusade and for their miniatures, lore and I have to tell I love them, I want to start with the miniatures but I don't know which faction is good for beginners, I don't mind how difficult are the miniatures to paint, I have 40k miniatures so I do have experience. I am confused on where do I start, does Trench have books like Codex to explain about the unites for each faction? I will grateful.