But I will also order the playing grounds extra, which are already in the basic box so I have them twice. In my opinion you are going to need more playing ground when playing with 4 players. As we were playing the demo, we both agreed, that the space for the units are just to small.
I think with all the extra tiles we get plus the scenarios i think there are enough. 21 tiles gotta be enough Im not sure if i will play 4p but the options wouldnt hurt but on the other hand if you get the Britts you get a extra faction and 3p. Still unsure.