Recommandations Française - routes avoiding traffic.

I took the Harwich-Hook of Holland ferry with a friend once, it was great. Overnight and sets you up for a good days touring afterwards. Off the ferry, we stopped at the first T junction and contemplated the map (well, our sense of direction) for a while, knowing that we were meant to turn left and cycle up the coast. Someone passing asked if we needed help and we said, "No thanks - we're going this way to Amsterdam" and they replied "Oh, you're taking the hilly route I see". Didn't know there were hills in the Netherlands - we quickly found out! 40m may not be that much altitude, but when you're repeating over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over and over again, it definitely adds up.