For placing goods on the market in England, Scotland and Wales, you must make sure they meet the requirements of the applicable UK regulation and any special requirements in that particular country.
Where mandatory conformity assessment needs to be conducted, it must be done by an UK-recognised conformity assessment body. EU conformity assessment bodies cannot carry out mandatory conformity assessment for goods placed on the market England, Scotland and Wales.
UKCA marking is required for many product types, specifically ones subject to specific directives and regulations that provide for UKCA marking. By placing the UKCA marking on a product, the manufacturer is declaring conformity with all of the legal requirements to achieve the marking and ensures validity for that product to be sold throughout England, Scotland and Wales.
For information on UKNI marking in Northern Ireland please click Trading with Northern Ireland | NSAI UK