Agreed.
How DO they do in Europe though?
Is it possible they run a seperate radial with a 5 or 3 amp MCB?
Do FCUs or similar exist there?
FCUs do not exist in Europe (possibly with the exception of Malta and Gibraltar). I don't think you find 5 or 3 amp MCBs either. Boilers are normally plugged in to a Schuko socket protected by a 16 amp MCB in the CU.