You don't even need good people skills, just being aggressive works, but you do have to be clear up-front: "stop right now, I am sure you fucked up this part: either prove to me I am wrong or redo it ASAP or I am not paying you for this" works much better than rolling out a list of complaints when they present the final bill.

In the UK, electricians do not have to be registered.

But I don’t know for sure.

Even that has been outlawed sadly. You can't fit your own fuse board and get an electrician to just sign off on it anymore - there might be people who still do it and give you a document saying they've done the installation, but in general it's not a thing anymore.

Of course absolutely nothing stops you from doing it anyway, then having a general electrical inspection done. If anyone asks just say it was like that when you bought the house already.

It is quite a racket in some towns, as some electricians will have an “expedited” relationship with the town’s inspectors, so you basically have to hire certain electricians if you want your project to move along smoothly. The electrician will come by and walk through for 5 min glancing here and there and sign the paper for $10k or $20k or $30k depending on size of the project.

Where I live, a homeowner is allowed to do their own electrical work. Must be permitted and inspected, though. When I've done big projects in the past, I've asked the inspector out at the start to ask for their advice -- gotten really good info that way.

There's a separate exam for solar installs. I took and passed that, but given that it is open book (you get the NEC book) and covers "only 3 sections of the NEC"), it was suprisingly hard.