To be fair, the OP has already indicated that such is his proposal/plan....... The thing is, using the plug & socket actually doesn't make the slightest bit of difference interms of legality or "paperwork". The socket and it's supply are a new circuit, and that is still notifiable. There are two routes, getting an electrician to "sign it off" is not one of them.
1) Option one is to employ a qualified electrician who is a member of an approved scheme. He (or she) can self notify through his scheme for a pittance.
However, as you will have seen, I've questioned whether it is necessarily straightforward and, in particular, that what gets plugged into the socket is "of no concern" to the designing/installing/certifying electrician. These 16A unshuttered plugs are not allowed for 'normal household use', so the electrician would have to know about the intended purpose, and be satisfied that installation of such a socket would thereby be compliant.By doing it my way I can do the shed wiring myself. I would only need to get a part p electrician to fit the 16 amp socket. What I plug into it is not his concern.
Even if the OP got an electrician to install a new circuit feeding something which was not a 16A socket, and the OP then 'extended' that circuit to a 16A socket (which extension would not be notifiable), the same issues/questions as to whether a 16A socket would be BS7671-compliant (hence, I imagine''legal' in the OP's eyes) would still arise.
Kind Regards, John
