Well, it seems nearly a year on, and I find myself in exactly the same position...
I've just bought the Roku, Specifically for the purpose of Watching NHL Gamecentre. I have the account, as from last year they allowed the UK to get Game centre. it's the perfect solution!
Except it isn't.
I couldn't find the channel in the channel store, got a really bad feeling about that... So I thought, might have to add it as a private channel. Tried adding it on the Roku Website, but then the website shows a little flag next to the box with the channel code in, that "this channel is not available in your area"
to say that I'm furious is an understatement. Just wasted a 100 pounds (not dollars, they are more expensive here) and nowhere on the NHL website, or the Roku website was it mentioned that the NHL app was only available in the domestic market, or at least that's what I'm figuring it is.
Unless someone knows of some way to get it on a Roku in the UK...?