Hi Vincentaj:
Without knowing your actual location nor what your departure time is from Gatwick, my tuppence-worth might not even be worth, erm, tuppence!
But I wondered if you were coming from somewhere with a good and fast rail connection to London, you only need a taxi (or the Underground if not overburdened with luggage) from that terminal across town to Victoria, from where a frequent and direct service runs right into a lift-ride from Gatwick Airport terminal.
It’s a lovely airport to navigate too, nowhere near as big as Heathrow.
Don’t overlook either the excellent National Express coach network. Very competitive pricewise too.
http://www.nationalexpress.com/home.aspx