Done it loads of times but many years ago so sorry info. might be out of date.
Depends if your wanting slow and easy or fast and furious I suppose.
Get across channel then two alternatives
1 - French way, nice scenery steady away to South of France avoiding toll motorways if you want down to southy of France, cross into Italy, along coast route (very scenic mountain tunnels etc).
2- German way, faster Autobahns, motorway juctions confusing, Austria Switzerland - nice
Once in Italy (North East or North West choice of 2 routes -
1. Former Yugoslavia, dodgy when we did it (just before war so we went through in one day with hardly a stop), think it's better now. Take scenic coastal route or faster motorway almost all way down through Macedonia.
2. Take ferry to Corfu from Italy - Venice, Ancona or from South Italy, Bari., Brindisi. Fantastic ferries, like a mini cruise and relatively cheap - dolphins, flying fish good cheap food.
Watch out for Mafiosa in South Italy (serious but no offense to Italians, certainly no offense to Mafia ), weve had a boat nicked, passports gone, car broken into on different occasions and many people we know have had similar experiences. Not a problem if you keep an eye on your stuff.
As I say things might and probably will have changed but enjoy your trip because the journey is just as important as the destination if not more so.