Ok, so I moved my HomePod to the TV and connected it via my Apple TV, went to Netflix then searched for Dolby Atmos, to bring up that content, but it was only showing 5.1 when I selected those titles, it was the same when I paused it.
i then contacted Netflix and they told me to go into my account settings and make sure I was streaming at high, not auto. It was at high but I flicked if from high to auto, saved then went back and changed it to high, then atmos suddenly appeared on my screen, and all atmos titles on Netflix now play as they should.
I then contacted Disney live chat and they advised that they don’t support atmos at the moment through homepods, hopefully the update will come, but atm don’t waste your time fiddling as it’s not working.