If you want them to say United Kingdom, then say it. Obscure one word comments aren't useful or transparent.
Sadly even UK is not right here. We are the United Kingdom of Great Britain and Northern Ireland.
If we do not include NI, then we are just Great Britain.
Most of us are confused about it too.
And the alpha_3 for The United Kingdom of Great Britain and Northern Ireland is GBR.
The Western European Archipelago is a complex place.
Well, the ancestor has a point, sort of. England conquered Wales, Scotland, and a bunch of other parts of the Earth, and only grudgingly became the "United Kingdom of Great Britain and Northern Ireland". Historically, its relationship with everyone else in Britain, much less the rest of the world, have been somewhat strained.
By the way, any news on the Scottish independence thing?
England didn't annex Scotland after an invasion. Scotland agreed to a union after their economy got rekt by a failed colonisation scheme and a famine.
If anything it was the other way round - the Scottish king took over the English throne