There are a few members who have driven down to Corfu, one in particular does most times. I pondered over the idea myself for a future trip, and using my Autoroute 2005, I plan in a route from my home town, via Dover, and down to Italy, either Venice or Bari (further south), and then plan the ferry from there.
From those who have done this trip, it appears that 3 days, is the norm. Remember the ferry from Venice is 23 hours.
The above link is a previous topic on this subject from back at the beginning of the year. You can also do a search (magnifying glass icon), type in Driving to Corfu in the subject box, and this will bring up lots more topics on the same subject.
Other members, in particular those who have done the drive will see this in due course and hopefully give there ideas on the subject. In the meantime, I hope this gives you something to look at.