Which left us with some gaping holes through to the living room. I used some deep gap filler, and a filling knife, and filled them as best as I could.
I left this for a few days to go fully hard, and then used some sandpaper to sand it down. I've no idea what grit size I used, I just picked up the first piece I found in the garage! It seemed quite coarse, but when I touched the wall afterwards it was super smooth so I didn't bother looking to find any finer sandpaper.
I then touched up with the wall paint, and I used a dry roller to run over where I had touched up to get rid of the brush marks, I also used this opportunity to touch up a few marks that we have accidently made on the walls since we painted it, not that long ago at all - oops!
For example this one, where Dan made a mark and then tried to rub it to get rid of the mark...
Good as new now. You'd never know there was ever a hole there now: