Going from Calais? Then really there are no interesting roads on that way up. Did a weekend slog to Apeldoorn and did the Calais/tunnel route because it worked out £80 cheaper than the ferry from Harwich-Hook including petrol for the bike!
Was one of the most boring rides ever. At least you don't go near the Brussels ring road
I can vouch for specialone's comment, there is one particular slip road that is like a moonscape. The Dutch people more than make up for the boring roads though
Chris