Thanks all! :)

Once height is adjustable initially, it's not something I'll need to change, so one of those T shape ones should be sufficient.

I've got this triple monitor stand.
Wanted it to be stand alone rather than attached to the desk.
It's heavy, chunky and obviously has a lot of adjustment points, but it's good and does the job once you've got it setup. Happily holds 3 x 24" screens

https://www.vonhaus.com/vh_en/triple-monitor-mount-stand