On Tue, 20 Oct 2020 12:43:03 +0100, John Rumm
wrote:
[snip]

With the 18th edition RCDs are pretty much unavoidable on most circuits,
since all sockets now need them, and the cable protection requirements
mop up most of the others. Moving forward, all RCBO installs are the
sensible way forward for all but the most budget installs IMHO.

A few years ago I asked an electrician to fit the full set of RCBOs.
He said this would be far too expensive and unnecessary. I asked him
to get me a price and he came back and said it cost less than he had
expected. I told him to go ahead, which he did. He ultimately
conceded this was the 'way to go'.