Book with Easyjet before 25 January 2013 (it doesn’t matter when you fly, you just need to book before this date) and you will earn Double points on your booking.
Combine that with the current Easyjet “under €50 flyaways” offer, and you may get a very good deal.
To collect Nectar points with Easyjet, you must log in to your Nectar account at www.nectar.com and book through this. Do not go straight to Easyjet.com. Full details on joining Nectar/signing up online (and even getting a card in Malta, for free) are here.