Ok, let me see if I can explain this:
England is a country.
Northern Ireland is a country.
Scotland is a country.
Wales is a country.
England, Scotland and Wales make up Great Britain and are all on one island.
England, Scotland, Wales and Northern Ireland make up the United Kingdom.
The proper term is "The United Kingdom of Great Britain and Northern Ireland"
There is no king in this kingdom at the moment but Queendom just doesn't sound the same.
No one really cares anway.
Did I get all that right?