The problem is when some one in authority is alerted and they require some expensive change.
I was watching a video about this with solar panels and batteries, and it did seem really daft, an inverter fitted rated at 10 kW but in the software reduced to 3.xx can't remember the figure, but it was the maximum export allowed, they had been told there were upgrades in the pipe line, so it could be reconfigured once done, but it seems the inverter was not registered for use in the software reduced form, so had to be ripped out and two 5 kW inverters replaced it, and just one set to export the full 5 kW, so in real terms exporting more.
No court case, it was simple, comply or we will disconnect the supply, even the DNO guy admitted it made no sense, but he insisted the change was made.
Back when I first started, to get a supply, the DNO as it was back then, would inspect the installation, and if it did not comply, you would not get your connection. Over the years, the situation became more relaxed, often getting a supply to an empty consumer unit, with maybe one socket.
But it seems, they can still refuse a supply, maybe rare, but they still it seems can. We also have the LABC who can identify poor installations, but they it would seem need to use the courts to force their point, but in the main, the threat is enough.
As to fitting a generator outside, and not connecting to the grid, not sure what can be done? We are at the moment seeing a battle between councils and central government over EV charging. With cables over the pavement. And also some debate over plug-in solar, as to what is allowed.
Even consumer protection has brought a case against passing and electrical installation as safe when it was not, so we don't even know who the Policemen are.
To my mine my credentials work against me, as I can hardly say I didn't know it was dangerous. My qualifications show I do know, yet still I have a battle getting the LABC to accept my signature, I did in the end, but it was not easy.
Personally I don't care what the regulations say, I want a safe installation, even if I could use just 2 RCDs I would say the risk of being plunged into darkness is too high, so all RCBOs in my home, but as to type A, only 2 changed, and that only because needed changing anyway.
Bring back
@ban-all-sheds all is forgiven.