Kingdom of Heaven Directors Cut Digital

Hi guys, can anyone help? I can't seem to find a digital version of the directors cut to buy anywhere. I can only find Blu-ray's. What's the deal? I don't even remember the last time I watched a movie on DVD or blu ray. In fact most of the time I get a chance to watch movies is downloaded on my tablet during my breaks at work, usually pulled up in a layby or carpark somewhere.

Edit: I'm in the UK.