Paul,
I'd just like to pick up on a point in the List of Non-Notifiable work, that I think has been overlooked.
IMHO, I think that the Upgrading of an Earthing/Equipotential Bonding Conductor, is a task that should be left to suitably qualified persons only.
The Electrical Safety level of an Installation, DEPENDS on it's Earthing/Bonding conductors, should one of these be of inadequate size, installed incorrectly or damaged during installation, who will carry the can for the deaths/injuries caused, by this, because any DIY person would plead ignorance. [Linked Image]