OK - I have run the numbers:
Either way we will pass through Zeebrugge or near enough. Zeebrugge or Hook of Holland to Luxembourg is about 220 miles
Calais to Zeebrugge is 80 miles
Norwich to Harwich is 70 miles
Norwich to the tunnel is 170 miles
Skipton to the tunnel is 300 miles
Skipton to Hull is 90 miles
Me to Harwich is 110 miles
Me to tunnel is 180 miles
So for Tom and Sally it is 310 miles of driving to go on the Hull ferry, or 600 miles of driving to go via the tunnel.
For Peter it is 290 miles on the ferry from Harwich or 470 miles through the tunnel
For me it is 330 miles on the ferry or 480 miles on the tunnel
Harwich ferry is about £200 total return with two people and one car. Hull is about £240. The tunnel is about £90.