Somewhere on your TV's remote control, there's a button which lets you switch between using the set's internal tuner (which is what you're trying to do) and accepting a signal from an external source (which is what you've been doing with your Sky box).
To put it another way, when you're viewing Sky channels, your TV set is really little more than a monitor which you use to display the pictures. (The Sky box does all the real work). You need to find the button which turns it back into a 'proper' TV set, where the picture is sourced from the set's internal tuner.
With some sets, switching between 'TV' and 'Monitor' is done automatically. i.e., if the set detects that there's a signal coming from the Sky box, it automatically switches itself to 'Monitor' mode. Simply unplugging the Sky box might persuade the TV to switch itself back to (true) 'TV' mode. (If not, you'll have to look for a 'Source' button, or similar, on the TV's handset).
If you're still having problems, please tell us the make & model of your TV set.
Chris
PS: You can get all of these channels with your satellite set-up, with a Sky subscription:
http://en.wikipedia.o...channels_at_28%C2%B0E