In reply to Flinticus:
For what its worth, when I took my van to Norway in summer 2018, after looking at the options, I took the car ferry from Hull to Zeebrugge overnight, drove to Hirtshall in Denmark (which is too far to drive and make the last ferry on the same day), spent the night in Denmark, caught the first ferry from Hirtshall to Langesund, and started driving from there....
There is also a catamaran from Hirtshall to Kristiansand, if you've got a strong stomach and don't mind spending a couple of hours watching people vomitting. I tried it once in 2017. I took the slow boat next time!
I've also done the drive via Copenhagen/Gothenburg, but this adds quite a lot more driving onto an already epic drive....