You can book a taxi via following methods:
Online: http://www.ontimeminicab.co.uk/
Telephone: +44 207 603 0333, +44 207 610 747
Yes, it's possible to pre-book a taxi with OnTime MiniCab, please contact the company.
OnTime MiniCab has both regular and air-conditioned taxis, please mention your preference at the time of booking.
Please contact the company on their helpline number to make any changes.
Generally drivers will meet the passengers at the arrivals on airport pick ups but do check with the company.