The first person with a home computer in the UK, not just a terminal, was probably computer music experimenter Peter Zinovieff, who bought a DEC PDP-8/S for his studio in the late 1960s, for the insane cost of around £80,000 (inflation adjusted to today.)
By the mid-70s the studio had turned into this:
https://www.thewire.co.uk/audio/tracks/listen_peter-zinovief...