New motorway is really easy to find/stumble over. As already said follow your normal route to Rouen, past the cows, on to the A13 then stay on it for about 10 miles you will pass a big service area about 1.5 miles before the turning. Even i managed to find it without getting lost, probabley because i had FS guide to getting there, the Michelin map and sat nav plus KPY directions that have always been spot on (he got me a route to Le Mans last year that avoided the N138) All in all a very quick drive now. I am looking forward to seeing the various cars flying past me on the way down Thursday. Only bad point (other than my spelling) is that there are quite a few places for the mobile speed cameras to be set up.
Andy