Half of this itinerary in 8 days would be rushed. April is generally cold, wet, and days are still rather short so youŽre not going to see as much as you plan on seeing.
You really miss too much, overlook (drive past) too many wonderful destinations by spending this much time on the road. I really wouldnŽt plan anything more than Paris and Normandy or maybe Paris and the Loire Valley. Paris, Normandy, and Brittany would be an 10 to 14 day itinerary. So would Paris, Normandy and the Loire Valley. Brittany itself is too far to even consider including it in an 8 day itinerary.
To me this is checklist tourism; saying you have been to a number of locations but actually seeing none of them. Obtain a copy of the Michelin Green Guide for Normandy and follow some of the suggested driving itineraries. YouŽll have a much better vacation.