Many years ago my father built a garage and it took him possibly a couple of
years to fix guttering. The principle reason was to get out of paying
increased rates in those days. This was a build wasn't rated until it was
signed off. Eventually because it was in use he capitulated.

However with Part 'P', what's to stop a notice to include rewire, adding of
additional circuits, circuits to (unbuilt) outhouses and sheds etc with the
intention of never "finishing" the work?

Is there a time-limit for the completion of work?

When sold it would be up to the new owners to choose whether to have the
work "finished" or inspected.

Where am I going wrong?