I have the Sony 40W4000 1080 HD Model with inbuilt Freeview, but do not use this facility as I have recently upgraded my Sky to Sky+.
Is Freesat built into yours ? In your case the Dish would have been connected directly to your TV via Aerial input for Freesat which is not the case with the Sky Digi Box as the output from Sky Digi Box enters TV via the Scart Lead.
You should still be able to get the Freeview Channels in full if you switch Off Sky Box and access Freeview facility.