I haven't downloaded or purchased, but apparently, you must have at least iOS 8 to download the app. Also, if you've previously downloaded the NT app, you may need to update that app before the Corio. purchase will show/download.

I've also heard that downloading on an iPad is more straightforward than a phone.

People in the UK and US have mentioned it on twitter, so I would think that it's available on both sides of the pond - and likely in all other countries.

Technology - eh.