Ironically London is one of the worst served places. Outside of hyperoptic noone is focussing on flats (MDUs), and inner London has a lot more apartment buildings than elsewhere.
I think partly because it's congested and expensive and awkward to install stuff. I'm in the center with 8 Mbps adsl over copper lines. One of my friends got 1GB fiber to his office put in but had to pay ~£3k for them in install the line.