I would guess 13 to 14 hours in the sky but you would probably have to stop a few times.
17hrs, 15 min - British Airways - 2 stops Source - http://www.expedia.co.uk/
Distance between Atlanta, Georgia, United States and London, England, United Kingdom, as the crow flies: 4218 miles (6788 km) (3665 nautical miles).
Hello, it would take you approx 25.5 hours of non-stop driving to reach your destination. A grand total of 1626 miles. (city limit to city limit)