Or, from Wikipedia (which is usually incredibly accurate for airport information, often beating airline's own websites to announce changes), BA flies to:
Algiers, Alicante, Amsterdam, Antigua, Barcelona, Barbados, Bermuda, Bordeaux, Cancún, Colombo, Dubrovnik, Edinburgh, Faro, Fuerteventura (begins 13 December 2014), Genoa, Glasgow-International, Grenada, Jersey, Kingston, Larnaca, Lanzarote, Las Vegas, Málaga, Malé, Malta, Marrakech, Mauritius, Naples, Nice, Orlando, Port of Spain, Providenciales (begins 29 March 2015), *** Cana, Rome-Fiumicino, St Kitts, St Lucia, Salzburg, Tampa, Tenerife-South, Tirana, Tobago, Turin, Venice-Marco Polo, Verona
Seasonal: Bari, Bodrum (begins 26 April 2015), Dalaman (begins 26 April 2015), Cagliari (begins 26 April 2015), Catania, Friedrichshafen (begins 20 December 2014), Geneva, Grenoble (begins 20 December 2014), Heraklion (begins 26 April 2015), Ibiza, Innsbruck, Paphos, Pisa, Rhodes (begins 29 April 2015), Thessaloniki
http://en.wikipedia.org/wiki/Gatwick_Airport