Technically the UK has left the European Union, but from the traveller’s point of view, nothing significant has changed during the transition phase. This comes to an end at 11pm GMT (midnight Central European Time) on 31 December 2020.
After that, life for British visitors to the EU becomes very different. The one exception is for Ireland, where very little changes: notably customs and motor insurance rules.
For everywhere else in Europe, these are the most critical changes.
Even if you have a burgundy passport with “European Union” on the cover, it will continue to be valid as a UK travel document. The problem is, from 1 January 2021, European rules on passport validity become much tougher.
On the day of travel to the EU (as well as non-members Andorra, Iceland, Liechtenstein, Norway, San Marino, Switzerland and the plucky Vatican City)