Just curious - will the Bed Vizualiser plugin work on a circular bed?
It should do, yes. There may be some settings you have to change to tell it that it should be circular but otherwise it is intended to work.
I couldn't see any settings which state the shape of the bed - perhaps it picks them up from Octoprint profile?
Yes a quick poke at the code confirms it does use the printer profile in OctoPrint.
Thank you Charlie 
Yes, it should work with circular bed. The visualization will look a little strange as it will cut out the corners, but Charlie is correct, it pulls from the printer profile, and there is also a option in the plugin's settings to use center origin.