Indy,

I may have misunderstood during the Zoom meeting what you were looking for!
The website owner needs to set up their own 123-Reg or other account and register the desired domain. (£11.99 + VAT). Their new authentication process sends a text or email to the account holder so no-one else can easily log in to the 123-Reg account. For this same reason it would be difficult for anyone else to set the DNS as required. 
What I can do would be to talk the owner through the process on the phone.
Your table also suggests I might create the e-Voice website for them - that's not something I would want to get involved with....
Regards,

Roger