Sky used to call this service freesat, however with the release of Freesat from itv and bbc i think they have now changed the name of it, and i dont know the new name so cant help you there.
With the other part i can help, to get the use of the sky+ feature from sky you will have to pay them a small fee(i think its 10 a month) for the use of the recording facility without a normal subscription, if you are not a subscriber and dont pay that money then you cannot use the recording facility.
If you decide to go ahead with it then you will also need to get 2 more wires added to your current dish as sky+ requires 2 ariels for twin recording.