Ah, I had become a bit lost on the King Arthur release timeline. I thought Fallen Champions was King Arthur II, but not so. It's actually a standalone expansion for the first game which bridges the storyline between Arthur I and Arthur II, and it came out earlier this month! Sorry, I missed that entirely. It has its own timeline, map, quests, heroes and so on. You can see all that in action in the gameplay trailer below.
I have to say that I rather like the King Arthur games. They are a sort of Total War-lite with more RPG stuff for your heroes and a good dose of fantasy nonsense. Honestly, I don't know how Neocore are churning out all these games.