You can book a taxi via following methods:
Online: http://www.melanntravel.co.uk/
Telephone: +44 122 620 0360
Yes, it's possible to pre-book a taxi with Melann Travel - Airport Taxis, please contact the company.
Melann Travel - Airport Taxis 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.