You can book a taxi via following methods:
Online: http://www.unicorntransfers.co.uk
Telephone: +44 203 384 3843
Email: info@unicorntransfers.co.uk
Yes, it's possible to pre-book a taxi with Unicorn Transfer -london Airport Taxi, please contact the company.
Unicorn Transfer -london Airport Taxi 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.