People going to Gatwick Airport will be able to use their Oyster card from 11 January, as the station has been placed on the London Tube map for the first time. In the largest map ever released by TfL, the stations from Merstham to Gatwick Airport have been added. The map also depicts another recent change to the Tube system – the creation of Zones 2/3 in east London.
Source: Gatwick Airport debuts on London Tube map | Home News | News | The Independent
For another idea re Gatwick Airport and London Underground (and a lot of other stuff) visit this post