When you're watching something in a catch-up app (BBC iPlayer, ITVX, Channel 4, etc.), you can quickly get back to live TV.
Standard exit: Press the Back button once to exit the catch-up app and go to the Freely homepage.
Quick return to live TV: If you want to skip the homepage and go straight back to the last live channel you were watching, press and hold the Back button until the live channel starts playing.