Barcelona El Prat Airport is served by Monarch and Ryanair from Birmingham and by Ryanair from East Midlands: http://www.aena-aeropuertos.es/csee/Satellite/Aeropuerto-Barcelona/en/Page/1045569607363//Airport-destinations.html Reus Airport (which has a direct coach link to Barcelona) is served by Ryanair, Thomas Cook and Thomson from...
The coaches from Reus and Girona both take just over an hour. (I've used the service from Girona and can recommend it). Using those airports can often help you to find far cheaper flights (or flights at more convenient times) than flying directly into El Prat.