17.5 hours (est.)

My flight for Heathrow leaves at 23:25, so I'm getting picked up to go to the airport at 2100 (9pm) this evening. My flight lands in Nice at 19:30 tomorrow, likely arrival at hotel would be about an hour later, making it 20:30 tomorrow (Sunday). But, there's a 6-hour time difference, so it works out to about 17.5 hours travelling. The return home looks about the same, but the time difference goes the other way.