You certainly can just move in and make yourself at home. It's up to the owner to turn up and have you chucked out (for breaking and entering, tresspass etc.). After six years, if the owner hasn't done that, it's yours.
EXACTLY what I'm proposing I should be able to do with the domain. Let me buy and use it until the current owner says he wants to use it.
See the point above and in most posts I've made on this thread.
10 to 12 years. Anyway we are arguing over examples. You can't buy the domain if it is not being sold. You may be able to request it from Nominet (the UK registar).