Plex - Virgin Media and Apple TV 4K


I have some how formed an impression that you can have the channels you receive on your Virgin Media streamed through Plex, and while under this impression I went and paid for a Plex Pass two days ago.

Now I'm a member paid up, instead of being happy I am a little disillusioned, as it does not seem to be as I understood "simple and straightforward" to set the TV streaming up.

Can someone please clarify if another piece of equipment is required a "Tuner" ?
Can someone also explain where it fits in the configuration physical and logical please. ?
So some how it connects to the Virgin box and retransmits the channels through Plex, so are you stuck looking at the same programs as those using the Virgin Media box ?
Finally what is the benefit ?

The HDHome Run Box is almost €200, I pay a Plex Subscription of €5 Monthly its €11 a month for a second Virgin Media Box, so for what I'd spend here I could pay for 3 years of a second Virgin Media box... Why ?

Hopefully its all very simple to set up and very worth while and I simply have misunderstood....!!!!