You could have done the UK series instead of the U series if you wanted (or bent the rules and done both ). It explains how in Chapter 2 of the walkthrough. You can check out the cover art of the modules here if you want to see which module is which. The G series (Giants) is in the works now. There may be a teaser map for them in the game, but I don't remember for sure.Did I miss any major maps/quests so far?
The walkthrough gives no real info about the UK series other than how to start. I can get to Piney bluff and 1 map to its west but can get no farther in this series.