Doesn;t it say on the site when the easyjet flight timetable is renewed? We flew to alicante in the summer and easyjet were fine, the only thing I worried about was the 'first come first on' policy, as I was flying alone with 3 kids and wanted (obviously) to sit together. We checked in the night before so as to be in group A - first group on the plane.
I can't remember but we were only one-way anyway (went to barcelona then cologne then Amsterdam ) However my firend has flown to alicante today and she couldn't book (in Feb) for this halfterm until about 3 months ago. She paid about £1000 for the 4 of them, return. Not as cheap as you'd think.
Try comparing prices for say christmas week. that's high season i think.
Register in Easy Jet/RyanAir/Jet 2/ThomsonFlights' mailing list, and then book the trip as soon as they release the offers (We have never paid more than 150 pp during the high season. Now we normally buy the tickets about 4 months in advance (earlier than that and they are normally more expensive) Another good place to visit is the Flight Comparisor of the Money Expert (don't know the addres but you will find it if you google it )