A good place to find out which routes are possible is Skyscanner
Here are some links to airlines who offer cheap flights.
Cheap flights from UK to Malaga :
British Airways - Regular scheduled flights from major British airports.
Easy Jet - flying from Bristol, east Midlands, Liverpool, Gatwick, Luton, Stanstead and Newcastle.
Monarch - flying from Luton, Gatwick or Manchester
Jet2 - flying from Leeds and Bradford
Cheap flights from Ireland to Malaga :
Ryanair - flying from Dublin.
Aer Lingus - Scheduled flights from Irish airports.
IBERIA- flying from Dublin.
British Airways - Scheduled flights fromDublin and Cork.
Information used with the permission of granadainfo.com