In message , at 08:20:46 on Tue,
16 Apr 2013, TraVeller13
remarked:
I go by plane to London and travel with my two children. Usually we take
cabs but it happened very often, that the cab drivers do not have child
safety seats - and we need two. I thougt of a car service that picks us
up at the airport an dirves us to the hotel.
Any affordable ideas?

It should be possible to pre-book a "private hire" vehicle (often called
an "airport transfer", and specify that you require child seats. You
don't mention the airport (Heathrow/ Gatwick?) but it's likely to be
around £40 to central London from Heathrow and £60 from Gatwick.
--
Roland Perry