If you've already got Sky equipment, you can buy a viewing card for a one-off payment of �20, which allows you to watch all of the free channels. You can then cancel your Sky subscription as long as you're not tied into an arrangement where you've agreed to pay for the service for a certain number of months. (If so, you'll have to wait until that minimum period expires before you can cancel). To purchase the �20 viewing card, phone 08448 244 400.
If you've not got Sky yet, you can pay a one-off fee of �150 and get Freesat from Sky for life.
Alternatively, you can pay just �75 for the same service. The 'catch' is that you also get a range of subscription services, free of charge, for the first 4 months. Sky will charge you �19 per month after that period, unless you remember to cancel the agreement (giving 30 days notice) before the trial period expires.
Chris