Generalplan Ost was the Nazi plan for colonizing central and eastern europe with German farmsteads. It's remarkably similar to American Manifest Destiny. Note that in both cases there were already people living in those lands that needed to be displaced. In the Nazi case, the people were to be eliminated, enslaved or Germanized if sufficiently Aryan.

Hitler respected the British as a mostly Aryan people and for the most part didn't care what they did so long as they didn't interfere with Generalplan Ost. That wasn't very realistic. Despite significant Nazi sympathizers in Britain, it's very unlikely they would have tolerated a genocide of white people in Europe. So the German war aims were primarily about knocking out Britain's will to fight, i.e. Battle of Britain, bombing cities, unrestricted submarine warfare.