Aye, I'm pleased and it's not as fraught once you know you're doing the right thing. The hole I cut is a neat rectangle, 210mm wide by 120mm high. I don't know if it's worth sticking the cut-out back on before hanging the cabinet over the top.
Yes it is. You know it is. If you don't do it, it'll be a job half done. You won't sleep proper at night. And fill the edges. And sand it proper. And fill it again - 'cos it won't be perfect the first time. And paint it after sanding it perfect...
If you replace the piece of plasterboard you've cut out, (fix it to the noggin with screws) then fill the edges and sand down, You know in years to come, your going to replace the cabinet with something else (or even get rid of the cabinet) The you'll have less work to do when you take the cabinet down.
Okay, I'm going to refit the cut-out (will it be a stuff-in then), I'll fill the edges but I ain't sanding it. Thanks very much for your humorous, yet valuable advice.