Phew! I probably should re-read that page about UK addressing anyway because the Haverfield Estate here has lots of housing where I'm not sure if they are flats or townhouses or maisonettes, whether they should have a housename or a streetname, a parentstreet, unit numbers or housenumbers. Is there a simple flowchart somewhere that gets you to a consistent answer after answering a few questions?
This block is an example - I don't know how the apartments/houses are numbered inside, nor exactly how they are divided up by floor.
https://www.openstreetmap.org/way/23918393