I have it! Just went out to see if I could get the new Campaign book and I did! Just been flicking through it now. Looks great fun. What it basically is, is a campaign report featuring 8 players, with all the additional rules you´d need as a group of players to play this campaign as well.
Haven´t read much, but did notice that the actual rules for Siege Battles and Underground Battles, while in there, only take uo about 6 pages in total. The book has 96 pages. Still, they are in there, ready to be used!
Right, I´m off to read this book cover to cover and see if this campaign is fun enough that´I´ll try and pitch playing this to my mates! Of course I should be painting stormvermin because I need 26 of those this Saturday but they can wait, right?