Further to the previous posting, I'm in a pedantic mood tonight, so here are the definitions of GB, the UK and the BI :-

Great Britain is the official name given to the three countries of England, Scotland and Wales and also includes the small adjacent islands EXCEPT the Channel Islands and the Isle of Man.

The United Kingdom consists of Great Britain and Northern Ireland. The Isle of Man and the bailiwicks of Jersey and Guernsey are NOT part of the United Kingdom. Nor are they part of the European Union. They are British crown dependencies.

The expression "British Isles" is geographical and not political. They are a group of islands consisting of Great Britain, the whole of Ireland, the Orkney and Shetland Islands, the Isle of Man, the Inner and Outer Hebrides, the Isle of Wight, Scilly Islands, Lundy Island, the Channel Islands and many other offshore islands.