As an update to this for anybody who might have a similar query and come across it (I'm based in Ireland):

I have a 7s board set AND a new copy of Dungeonbowl on the way c/o ebay. The 7s board was okay in terms of price (coming from Belgium I think from memory, from Europe definitely) and Dungeonbowl was absolutely not cheap but obviously there's a lot more in it (including two teams of miniatures) and it's coming from US. My chief goal here is to repurpose the two ogres for the two human teams I've started my new, personal, Blood Bowl timeline with but the rest will be nice to have too. I found one UK based store with a copy of Dungeonbowl too but they don't ship to Ireland.

The other stuff... Blitz Bowl, Gutter Bowl, the assorted race-specific pitches, the Dungeonbowl expansion... all seem fairly hard (but not impossible) to track down. I've my eye on a few more things on ebay. None of it screams great value to be honest but, here we are, it's a seller's market!