There are projects which are entirely self build where all the work is DIY and the local building inspectors accept the situation.
In 1981 my wife and I self built our house doing all the work ourselves. It was a lot easier then but recently when we had a new kitchen intalled I did the electrics and the were happy for me to sign that the work complied with a safe standard as I had proven my ability.
I am told that some authorities will do ( are doing ) the same if they are convinced the self builder has shown themselves to be sensible. So if you can show good practise in other trades and a good knowledge of regulations and no corner cutting they may accept you to self certify your work.
In 1981 my wife and I self built our house doing all the work ourselves. It was a lot easier then but recently when we had a new kitchen intalled I did the electrics and the were happy for me to sign that the work complied with a safe standard as I had proven my ability.
I am told that some authorities will do ( are doing ) the same if they are convinced the self builder has shown themselves to be sensible. So if you can show good practise in other trades and a good knowledge of regulations and no corner cutting they may accept you to self certify your work.