As you have an existing service they'd likely just send out the extra kit and instructions on how you plug it in, i.e. standard activation fee.
If you pay extra you get an engineer to visit (obviously those with no existing Virgin wiring pay for the engineer visit always)
So short answer, they would use the existing feed, so using CAT5 to take it to your study is the best way
They will send out engineer who will leave what you currently have in place but run another cable from the omni box (this is one on your building outside) to your room you want.
They will need to send someone out because he stated he will be switching to phone service as well which he does not have phone point for already.
So it is simple they run new cable to the study so you will get telephone and internet feed of that (virgin router is rubbish so only use that in modem mode with another router)
Edited by mortmaru (Sun 15-Oct-17 22:06:08)