If you can bring yourself to cancel, and potentially have Sky premium channels stopped for a few weeks, you'll be able to get a good deal to "come back to Sky". They recently offered me everything for £32 a month. I said no, they then called me a week later and offered the lot for £25 a month for 18 months + a one-off £10 admin fee. There's no way I'd be willing to pay full price given how the content I want is now split up across multiple paid providers.
I said potentially lose access to Sky premium channels for a few weeks, because often they'll call you during the 30 day notice period to offer you a great deal. They very rarely offer you a good deal anymore just threatening to cancel, you have to go through and process the cancellation and start the notice period to get the best offers.