"we will have the new UKPound instead."
This one always make me laugh. The "United Kingdom" consists of two kingdoms - England and Scotland. Although nowadays thought of as separate countries in their own right, Wales and Norther Ireland have never been kingdoms - the former is a principality and the latter a province. There has never been a true king of Wales or Northern Ireland.
So, if Scotland gains independence, the kingdom of England will have no other kingdom with which to be "united".
So how would a "UKPound" work, exactly?