Wizard, I would need to go and buy one of those capacitors.
In the meantime, a technician from the suppliers is going to ring me to talk me through it. Hopefully, that will work and I can post instructions for any future user.
I have the lathe working now. The speed is adjusted with the pot thingy on the inverter and the lathes stop/start button is also programmed into it. I'll do up a list of instructions for this inverter for the benefit of anyone else purchasing one in future.