Ruprecht and Joerg have no knowledge of today's UK. Too bad, because London is on the Thames River. York and Cardiff are also in England. Dublin and Belfast are in Ireland. Edinburgh might be Emborg.
I think they forgot the coin with the stars. Stars on maps usually represent capital cities, or major sites.
The site they ended up finding sounds like another landing strip for the spaceships. The radiation warning probably means there is an energy source for the complex. I wonder what else they may find.
That the men have had their heads ripped off indicates a powerful beast, not humans murdered these men.