Well I will, because "up to you" is irresponsibly inadequate - it isn't just he who is affected - everybody else who later uses or modifies what he does is at risk if he does not do it properly.
Saying that it is up to him whether he does or does not make reasonable provision in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury is wrong - it is NOT up to him - it's a legal requirement that he do so, not some optional choice of his.
I was not saying he has a legal right to decide if to comply with Part P, what I was trying to say it is a poorly written document and so all we have for clarification is case law, since the only cases seem to be where there is something very wrong, or some one said they are scheme members when they were not, it is near impossible to second guess what the courts would say, in real terms is a DIY guy gets it wrong, and the LABC find out, they say rip it out again or we will take you to court, and the DIY guy will rip it out, so there is no court case.
I think we all know what should be notified, however until some one is taken to court for fitting a FCU with cable to a fixed socket, we can't say 100% if allowed or not, we know that scheme providers feel it does not required notifying, but they don't make the laws, and it is using BS7671 forming a new circuit. If instead of using a FCU one uses a mini consumer unit, although it is doing the same thing, it seems scheme providers feel that should be notified, however again it would need a court case to verify this. A consumer unit is a type tested distribution unit, and should be used where in the control of an ordinary person, it would lose it's type testing if you were to fit parts not sanctioned by the manufacturers, so if you do that then it is no longer a consumer unit, it is only a distribution unit, we all know if we modify it that does not mean it does not require notification, however as written it may not count, again up to courts to decide, and until some one is taken to court we can argue until cows come home, but still no answer.
To my mind we all know what we should do, but it is up to each one of us, to read the published paperwork, and make up our own minds, I see no point in trying to reword what the documents say, it is up to you the reader to make up your own mind as to what is allowed, it is not up to the forum members to try and say what the law says, it is up to person doing the work to read it and make up his own mind.
As it stands if I make a 4 way socket on an extension lead and plug it in my kitchen that does not require notifying, however if I put a couple a screws in the wall and fix it to the wall out of the way of any spills on the counter and use some cleats to hold the cable out of the way, then technically it becomes fixed, so I should notify the LABC before I do it. I think even the LABC inspectors would say don't be daft, however in Wales in theory you should.
I am really not interested in going through what is and is not required, that's up to the poster, he can read just as well as me, and he can also decide when clearly it does not make sense and does not really require notifying, with the 4 way extension lead if I buy it then it's type tested so I don't need to notify when using it. Blagdon still market cables for garden type tested so don't require notifying, OK in England the law has changed, but Part P was not written by the Welsh assembly, it was an English law which the English realised had gone OTT so modified it, but left the old one in force in Wales.
You will note the poster has not set his location, so how can we really tell him what to do?