ViaMichelin quotes the total journey time as 21 hours 51 minutes. That includes the time on the ferry but excludes the time waiting for the ferry and driving breaks.
If you're in a real hurry, you could probably get there in 2 days with two people sharing the driving. With one driver, who is used to prolonged driving (such as an experienced long distance lorry driver), 3 days would be more realistic. For a more leisurely drive, allow 4 days. To do some sightseeing on the way, allow closer to a week. (ViaMichelin quotes the total driving distance as 2209 km = 1373 miles. The time taken will depend upon whether you're determined to get there as quickly as possible or whether you want to enjoy some sightseeing along the way).
To plan your route, go here:
http://www.viamichelin.com
Chris