My understanding is you can get BOTH at the some time, sort of. Keep the copper (if you still want it), but use the fibre to the cabinet, to get considerably higher broadband speeds, by using a fast provider and suitable box (they should supply for free).
This limits you to around 70Mb/s(download speed)/18Mb/s (upload speed), but that should be fine for many people.
The actual speed depends on the quality of your line and how far away it is from the exchange/boxes/etc. So may be different/less, it also depends on which provider you choose.
Many seem to refuse to offer, new landline services now, at least according to their adverts.
I.e. The landlines, are becoming increasingly obsolete in the UK. But there are issues, as you may need to have holes drilled in your home, an engineer needs to enter your home, have stuff rerouted, depending on your internal configurations, power a box of tricks, and have to sort out some other arrangement (£'s equipment plus possible extra monthly £'s fees, for the call services), to get phone lines (equivalents), working again.
Also no local electricity (power cut) = no phones/internet, except mobile phones, when you get the phone lines removed.
On the other hand. The all fibre (fibre to the home), solution. Is suppose to be considerably quicker (especially if you pay extra, for the high speed monthly plans), and more reliable (much fewer internet line disconnections/drops).