P & O North Sea Ferries have 2 for 1 deals on the Hull mini cruises.
I personally, do the Hull to Zeebrugge motorists mini cruise.
2 passengers (for the price of one) plus a car for approx £74.
Then as you drive from Zeebrugge to Dunkerque (hypermarket) - stop off at Adinkerke (Tobacco Road) and buy your 3kg of tobacco for 'personal use'. Another tip - Eat before you board and just have a coffee/croussant for breakfast, otherwise it's another £89 for two for meals.