It depends when you want to travel. Easter, Summer and Christmas are the most expensive times to travel.
Examples. I want to go to Jordan over the Easter period and for a 4.3 hour journey BA are charging nearly £1000. If I go to Jordan in May the fare is half that! Aer Lingus and Ryan Air wanted around £350 to travel BHX - DUB for New Year. Any other time (apart from weekends) it's pennies.