I found a good alternative to the Gatwick Express from the airport to London. On the arrivals level at Gatwick, there is a kiosk for National Rail. The cost of a one-way ticket to the city was about 9 GBP ($18). That included a one day pass on the London transit. There are a number of destinations from Gatwick (I went to Kensington Olympia). There are numerous connections to other National Rail / London Tube stations. The service is frequent and quick - I found it very comparable to the Gatwick Express, and somewhat less expensive.
Please sign in to post.