Whatever might be the appropriate state for the remainder of what has been called the United Kingdom of Great Britain and Northern Ireland if Scotland withdraws, there can be no question but that Great Britain would not be acceptable. Great Britain is an island,and Scotland is the northern half of it.

I suppose it would be possible to rebrand the successor state as the United Kingdom of Southern Britain and Northern Ireland. At least for the time being until the Welsh and Irish pull out.

Or maybe Little Britain?