Since 1 October 2021 you will need a valid passport for entrance to the UK. If you became a UK resident on or before 31 December 2020, you can continue to use your ID card to travel between the Netherlands and the UK until at least the end of 2025. Read more here.
1) Booking is not known at the ferry or shortsea terminal:
2) No customs declaration has been submitted to Customs:
3) The customs documents have not been (correctly) pre-notified at the terminal via Portbase:
4) You do not have a valid proof of identity:
Prior to your departure, use Portbase to verify the status of your customs documents at the terminal via the service Import Status or the Track & Trace Export screen of the service Notification Export Documentation. Register for these services at www.portbase.com/en/services/import-status and www.portbase.com/en/services/notification-export-documentation/.