Ilustrated man has already indicated the best route now.
Overnight ferry Harwich to Esbjerg (west coast Denmark) DFDS
Then it's a 2.5 hour drive to Hirtshals (northern tip of Denmark)
Ferry Hirtshals to Larvik, Sea Speed 1, Color line high speed ferry.
Or you can go Hirtshals to Kristiansand, (southern tip of Norway) Sea Speed 2, high speed ferry.
Both the same price.
Larvik is 2 hours from Oslo.
If your going to tour, I would suggest the Kristiansand crossing, then as you know, it is all E39, west coast fjords all the way up north. Stavanger, carry on north on the E13, or the real coast road, really beautiful, but time consuming.
Stunning scenery, but will take forever.
Larvik, is more easier to jump onto the E18, through Drammen, then hit Oslo, and up the E18 to Trondeheim, or as far as Tromso, take your pick.
Here to lust your appetite.