Master Plan West was a British plan for control of some parts of western Europe. It involved colonisation and would have included ethnic cleansing.
Ireland was to be fully annexed and ethnically cleansed of all Irish, with English sent over to replace them.
Normandy was to be fully annexed and ethnically cleansed, with a process of anglicisation beginning as soon as possible.
The exact plans designed for the lowlands were vague, but it seems Mosley wanted some sort of economic union or something similar, especially with the Netherlands/
British plans for Germany were never properly decided but many wanted some sort of influence over Hanover, an area which had formally been in the British sphere of influence.