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The app you're wanting is called TV Player. That contains all 5 terrestrial channels.

Now TV with an entertainment/movie pass (eBay is your best bet) sorts out your Sky needs. The movies are only 720p though so not the greatest of quality.

iPlayer isn't available yet for the Apple TV.

You should be able to pause what you're watching like with any other streaming app.

iPlayer is now available on Apple TV. So I My5 (channel 5), itv Hub, All4 (channel 4). I have not made the switch to fully Apple TV but I don't think you would miss anything.
 
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