Just to clarify things a little, what you receive via your Sky "receiver" is NOT Freeview.
Freeview is Digital Terrestrial Television (DTT) and comes to you via your TV aerial.
Free channels on Sky are FreeSatFrom Sky, and come via your satellite dish. There are also the channels you can receive if you have Sky equipment but no subscription.
There is also another (recently launched) Free satellite TV service, confusingly called FreeSat - which is nothing to do with Sky although you can (with the right receiver) use your Sky dish to receive it. The channel line up differs from FreeeSatFrom Sky as it includes channels such as ITV-HD which are not available on the Sky platform.