Unless I’m much mistaken, Virgin is fibre to the street cabinet, and then coax cable to the home. The new BT Infinity service is also fibre to the cabinet, but twisted pair to the home (unless it’s a new build, or trial area, in which case you may get fibre to the home).
With Virgin, everything comes down the coax cable – phone, internet, TV using a system called DOCSIS. The latest version of DOCSIS can support very high speeds – coax is somewhat better than twisted pair at supporting high speeds.
Edit: Generally, Virgin is very reliable, except when you have a problem, in which case they are somewhat understaffed. After 8 years of pretty perfect service, this week they decided to switch off my broadband. Small change in the provision, and because I have an old box, they won’t support it any more. Reported Monday, engineer Friday.