Girona is nearer, and also benefits from cheap Ryanair flights from many UK airports. Confusingly, Ryanair calls it "Girona/Barcelona" or simply "Barcelona", but that's just a marketing exercise.
Tossa is about a thirty minute drive from Girona airport. You can get a taxi for about E55 one way, or arrange a transfer with a company like ShuttleDirect for about the same amount. There are buses, but they are very infrequent, and never seem to tie up with my flight times. Car hire's another option, and there are some good deals on the web.
Tossa's a lovely place, much more laid-back and picturesque than most other Costa Brava resorts, especially in the south.
- Tony -