Frankly bizarre statements there. PN are offering FTTP, at up to 500mbps, but it's dependent on when BT enable it in an area. My contract's up in a few months, so I'd be interested in switching to that service, even at a premium, if only they offered it- and no, they don't tell you when it might be available either!
RE the phone: If you have a landline at the moment you can keep it, and go to one of the CityFibre ISPs and have the fibre as an extra line, or discontinue the BT line and switch your number. If you switch to the fibre for your phone line, the phone runs through the router. However, this will happen for you, me and everyone else in the country, regardless as analogue phone lines will be switched off by 2025, which has caused much angst, power cut means no landline. You'll have fibre whether you want it or not…The amount of data used by phone calls is tiny, he's talking total BS on that score.