The UK government introduced its own Conformity Assessed (UKCA) Marking programme for items sold in the GB (England, Scotland, and Wales) market on January 1, 2021. Northern Ireland has its own set of rules, which are outlined here. There is no mutual recognition of marks between the UK and EU.
What does the UKCA mark indicate?
The producer declares that a product fulfils the UK Regulations as stated in the applicable Statutory Instruments by affixing a UKCA mark to it and placing it on the UK market (SIs).