Looks like this forum is inactive but I'll post and update just in case someone stumbles on it.
In the end we purchased an Anet A6 3D printer.
I made a number of mods from Thingiverse.
Last week the motherboard died mid print. The printer just hung. All I could do was turn it off and when I turned it back on it reboot then hung immediately. Every turn on since then just displays a blank screen. I have tested the 12v supply which is ok. I've turned it on with all extruder, hotbed and steppers disconnected and still it only shows a blank screen.
I'm now awaiting delivery of a MKS Gen L kit as a replacement and will install the latest Marlin on it. Once it is working I'll be able to implement auto levelling.