From 1 January 2021, British nationals will be subject to more extensive checks. Travellers from the United Kingdom should carry a passport and arrive in good time at border posts for onward travel to the European Union. At border control they will have to take a separate lane from EU, EEA or Swiss citizens..
Everything you need to know about travelling to France : British citizen travelling to France
Travelling with your pet after 31st december 2020
You can no longer use a pet passport issued in Great Britain (England, Wales and Scotland) for travel to an EU country or Northern Ireland. You can still use a pet passport issued in an EU country or Northern Ireland.
When travelling to an EU country or Northern Ireland, your pet needs :
a valid rabies vaccination
an animal health certificate unless you have a pet passport issued in an EU country or Northern Ireland
tapeworm treatment for dogs if you’re travelling directly to Finland, Ireland, Northern Ireland, Norway or Malta.
These requirements also apply to assistance dogs.
Check the rules of the country you are travelling to for any additional restrictions or requirements before you travel.
More information can be found on the Government’s website on Pet travel to Europe after Brexit.