This from the RAC website
" Drivers with hopes of road-tripping through Europe later this year will have to trade in their GB car sticker or magnet for a new ‘UK’ version.
The current sticker used on the back of vehicles will no longer be valid from September 28, the United Nations (UN) has outlined. Instead, motorists will have to replace it with a UK sticker to drive on foreign roads.
Those with a GB number plate will also need a new sticker, or have to order a fresh number plate with the UK symbol.
The UN said it had received “a notification stating that the United Kingdom is changing the distinguishing sign that it had previously selected for display in international traffic on vehicles registered in the United Kingdom, from ‘GB’ to ‘UK’”.
Although no official reasons have yet been outlined, the move is thought to be a show of solidarity with Northern Ireland in the wake of Brexit. GB stands for Great Britain, which comprises England, Scotland and Wales, whereas UK stands for the United Kingdom, which comprises Great Britain and Northern Ireland.
The switch to a ‘UK’ emblem is the second re-vamp number plates have had this year. In January, Grant Shapps announced UK drivers would be able to drive on the continent without GB stickers thanks to a new registration plate with a Union Flag and GB sign.
He also tweeted an image revealing the updated look of a green number plate, used to signify fully electric vehicles and showcase the incentives of opting for a more environmentally friendly car.
British number plates have previously featured a GB symbol under the cluster of EU stars.
The UK government said in a letter to the UN that the change applies only to the United Kingdom of Great Britain and Northern Ireland and “does not extend to any territories for the international relations of which the United Kingdom is responsible”.
The new UK stickers will be available online, and in post offices and garages for around £1.50.
Looking forward to finally taking a European road trip? Brush up on every legal requirement and get pre-journey tips in our driver’s guides for every European country."