You can get 80 meg broadband from BT Infinity with fibre to the street cabinet, so you might need to offer more than 100+.

G.fast extends the fibre closer to the house but I suspect it's not very cost-effective unless the take-up is high, so perhaps it will mainly cater to rich people in suburbia.

We've know that fibre (FTTH) was the answer since the 1980s but all British governments have been too short-sighted and stupid to finance it.

Of course, they dug up the streets to install new pipes for the short-term benefits of North Sea gas, and they can find £50 billion for HS2, when they could have FTTH for less.