I am in the UK at the moment, overnight ferry from Ijmuiden in the Netherlands to Newcastle last night. You will need to complete this form
https://visas-immigration.service.go...r-locator-form
This was checked at passport control at Newcastle.
When I checked in at Ijmuiden with DFDS, the assistant at the counter told me to make sure to have this ready to show on arrival in the UK, apparently there had been whingeing from UK passport control about passengers arriving without this document. Officially you can be handed a hundred quid fine for not having it.
Mikee, I hope your travel is uneventful and you see your dad soon
Edit: form can only be filled out 48 hours or less before arrival in the UK. The system halts if you try to do it any sooner