Thanks for the advice guys. I figured it out on the PS4. It's just a slight variation of what brownstar said.
On the PS4, you create a 2nd user on the console and register it with a UK Address and UK PSN store account. Then when you login to your PS4 as that user, under the TV Video section of the menu bar, apps like the BBC iPlayer and Demand 5 appear.
Here's the trick.
Download them while logged on as your UK username on the PS4 console, but then you HAVE to go into the PS4 settings and choose to have the console designated as your "primary console". This allows other users on the system to access your apps.
Then you can log out of your PS4 and relogin as your regular username on the console. Then your Canadian/American apps (Netflix) will appear right alongside the installed UK video services like BBC iPlayer and Demand5. I've been enjoying it all for the last few weeks and the quality is great.