I regularly use the Gatwick-Malaga route. I am free to travel at amy time and therefore the decision as to when to travel is usually price driven. There are three "scheduled" carriers on the route; BA, Monarch and Easy. Holiday airline flights are becoming rarer and rarer, partly because it seems My Travel have effectively withdrawn from the Coats del Sol. Of them only Britannia operates a daily service., sometimes at diabolical times. Excel operates several times a week but only offers combinations of 7 and 14 days which is useless fro that market.
For most of the recent spring BA has been the cheapest airline provided you leave LGW @ 0630 and come back in the late evening. BA is the most expensive for the best times. Easy prices vary dramatically and can be very high. Monarch has been consistently offering the best value but its weekend prices can be as high as £175 one way plus tax.
A good target price for very early booking for mid week flights is £50 return incl tax. Easy very rarely achieves this.
Lesson; shop around before you buy. It is well worth 30 minutes on the internet.