sbiddle: If you have the box connected via HDMI you shouldn't be anywhere near the TV tuner - you should just be selecting the AV input that corresponds to the HDMI input.
(the practice of real science, engineering and management)
TwoSeven: This is just my thoughts.
On many TV remotes/TV Sets there is an ability to choose the 'source' of your signal. Each device connected to the TV is considered a 'source'.
If you connect an HDMI cable from your sky box to the TV, take a look at the label next to where it plugs in to the TV. It may say something like HDMI 1. When you select the 'source' on the remote - choose HDMI 1 and you should see your sky pictures. No need to do any tuning for this device.
The same applies for normal Television, however in this case you do require a TV aerial to be plugged in to the back of the TV. If the cable coming out of your wall from your aerial has a screw thread on the end, you may need an adaptor to plug it into the TV areal socket. Once this connection is done, you can then use the TV menu to tune in the digital TV channels (Freeview), and once done, change 'source' to the TV channel.
The same technique will apply (as connecting a sky box) if you connect a modern DVD player or Hard Drive recorder.