Following the UK’s departure from the European Union, U.S. export health certificates are now required to either follow the Great Britain model (for destinations within England, Scotland, or Wales) or the European Union health certificate model if shipping to Northern Ireland.
Attaché Report (GAIN)

United Kingdom: FAIRS Export Certificate Report

The United Kingdom, as a Member State of the European Union, has implemented EU regulations for the import of products of animal and plant origin.