Just cancel it every year. Moan about how its a luxury you can't afford. They'll instantly offer you some crap deal on the phone. Turn it down. Your now in your months notice. Expect at least 2 call from sky during the month offering you better deals, hold out for 50% off as thats what they offer new customers, if they don't offer you keep declining. They'll either offer you an acceptable discount 40% or keep decline and they'll phone again else just let it cancel and sign up as a new customer, preferably in the missus name. Plenty new customer 50% deals about on various sites. They'll also bomabard you personally with rejoin at 50% off deals by post after your month runs out.
Finally don't fall for any deal involving broadband. You can get broadband free from talk talk and sky just want to keep you away from BT who will give you free BT sport for taking their broadband. Although your probably still cheaper doing talk talk free broadband and paying for BT sport (Ive taken BT sport out on a rolling month to month contract, cancelled twice this year and been given a free month each time. Deals are there to be had.