It is the responsibility of the professional driver to do the check, but this can be done on their behalf by their manager.
From 1 January 2021, drivers travelling to the Port of Dover or Eurotunnel will be required to use the Check an HGV is Ready to Cross the Border service and get a Kent Access Permit (KAP).
A KAP will be required regardless of agreement of the outcome of the negotiations.
You can be fined £300 if you do not use the service when travelling through Kent or if you provide a fraudulent declaration.
The Haulier Handbook
A more comprehensive version has been published.