http://www.bestbikingroads.com/show_routes_in_selected_province.php?code=268
It is a good site A little bit clunky to figure out the routes though. I used it to help plan a route around Kent and Dungeness a couple of months ago.
CGB on here told me about it first, he said it was great for finding roads down near the Pyranees too :w00t:
Much better off with one of these: