I phoned my local building control dept. I was posing as someone who 'wanted' to do the right thing.
Turns out after a conversation that whilst you can submit a notice to your LABC and do the work yourself. However the fees are such that it is financially very disadvantageous to do this.
Whilst it is true that the fee for the LABC is 100+VAT (for up to £2000 quids worth of work) they are empowered in this matter to make additional charges for the building notice. [Section 12 something or other ...] The net result is that the LABC simply acts as an agency for sending a registered sparky to inspect the work. There are five organisations whose members may self certify. NICEIC, ECA, NAPIT ...
So effectively the law is use a registered sparky or pay for one through the nose via the LABC.
This law is effectively unpoliceable until something goes wrong. If you need to sell you might as well shell out a few hundred for a full test and inspect ticket.
If there is other work that is notifiable taking place then it might well be that a zealous LABC officer might be interested in Prat-P violations.
This year I'm too busy to sort out registration but I can see I'll have to bite the bullet sooner or later.
DIY has now become a subversive activity...