I assume from your post that you have a Sky box and a Freeview digibox. The best method would be for both Freeview and Sky to be connected to the TV via it's Scart inputs. The TV aerial cable would then be connected to the Freeview box and it is the Freeview box that then requires tuning, rather than the TV itself. Selecting either AV source from the TV remote would switch between Sky and Freeview signals.
If either box is instead connected to the TV by the aerial input connection the the TV will need to be tuned to the output channel of the box in question (it is normally in the channel range 34 - 39). Attempting to connect both boxes via "daisy-chaining" with an aerial cable can lead to issues if the output channel of each box is the same or similar.
The best picture quality will be obtained using the scart connections as outlined above - please try this and let us know the outcome.
Generally speaking, you aren't learning much if your lips are moving.