The Hull Rotterdam ferry is far better then Dover Calias. Like you said the fact that you get a "free" nights accomodation makes a huge difference. 12 hours drive in a day is doable after a decent sleep. I have done Grudziadz to Stoke in one go via Dover but thats a solid 20-22hr trip and the only time to "relax" is the 1.5 hrs on the ferry buy by the time you got some food thats down to 45 mins. When I worked out the costs for both trips I think the Dover Calias route was about £10 cheaper overall - not worth the saving in my opinion especially when the costs included evening meal and breakfast on the Hull Rotterdam route. I always use the A2 route to Poznan and then up to Grudziadz - I agree the road from A2 to A1 is a nightmare even in a Polish car let alone a UK one. Once you are stuck behind a lorry it can be miles before you can get a safe overtake unless you are proper Polish driver
Looking forward to the opening of the S5 link which they start building this year then it will be dual carriageway from A1 at Nowe Marzy all the way to A2 - that should cut down the journey time by another 1hr - 1.5hr easily.
Hope you had a good trip back. 2008 TDV8

S5 link from Gniezno to Nowe Marzy would change everything but surely that's 10 years away, unless you've heard something different. We were two cars behind a double fatality accident just south of Znin about 4 years ago so my feelings about the existing road are affected badly.

The loop around Gniezno started last year - i think that is planned to open autumn of this year which should finish just south of Znin. The section from Bydgoscz to Marzy is due to start very soon - they have already cut huge sections of forest either sidr of the road from Nowe Marzy to Swiecie. There is a big push to get everything moving because of uncertanty about funding from the EU if nothing is started soon. I beleive major construction (over 50% completed) needs to be shown by 2019 for funding to remain. But this is Poland so ìt could be another 5 years before they completed the remaining 50%  2008 TDV8

I don't think you can better a TDV8 Fattie , it's quiet , powerful , economical (MPG) , all the luxury and comfort you need
You can park it relatively anywhere and it doesn't draw attention

As said a Bentley arnage is a relatively cheap luxury car but you can't tow a horse box with it onto no6 Range Rover

Everyone needs a hobby