As you already presumably have the Sky dish, why not go for Freesat rather than Freeview?
All you will need is a one off payment for a Freesat SD or HD set top box and you should be away (no subscriptions)...:-)
Freesat STBs from outlets such as Argos:
If you decide to go the Freesat route, may I respectfully suggest you choose a Humax model, preferably HD?
The BBC was involved with the establishing of both Freeview and Freesat.