All London airports are covered. You can book the ride in advance.
The driver will wait free of charge for 30 minutes in all airports. If you enter your flight number in the title of your email when making your booking, then the driver will be able to track your plane. In this case, the free 30-minute countdown won’t start until the actual landing time.
If you exceed the 30 minute wait, any parking charges will be added to the final fare.