Sky Atlantic only broadcast the last episode of the current season of Game of Thrones on Monday evening, but BlinkBox, the Tesco service, already has it available for non-Sky customers on the streaming service - check out BlinkBox Game of Thrones. £17.99 for SD, £23.99 for HD. It's also available (for slightly more) on GooglePlay. That's bloody quick availability - NowTV customers probably won't get a playable version through on demand for a few more days yet!
The Blu Ray and DVD won't appear until next Spring, unless the folk at HBO have a change of heart. (I was surprised to see this year's HBO biggie True Detective out on disc earlier this month, just a few weeks after Sky finished broadcasting it.)