Gosh, Mass Effect is less than three quid. Again. But at least this offer undercuts most of the usual suspects by an extra 50p.
So, if you don't already own Mass Effect, go rectify that situation. There is no point playing Mass Effect 2 our 3 before playing the original. If you do, the Normandy will be just a ship. Wrex will be just another Krogan. Nothing will matter. Everything will be ruined. We will ring you up only to sob, quietly, over the line as you re-evaluate your life decisions.
You must - must - play the original first! If not, you're doing yourself out of one of the greatest interactive storytelling experiences of all time.