CNBC UK doesn't seem to have a live feed channel through any kind of official means as far as I've been able to find online. You can watch specific programs/snippets of programming on their app on roku, now tv, and on their mobile apps.
There are live stream services about on the internet but they are not official and tend to be bloated with adwares. Fancystream.com, oklivetv and several others.
Only real way is via satellite or an in app subscription