405 TD Estate wrote:
No - why on earth would you want to do that?!

So the wall is completely flat and smooth before putting the insulated
plasterboard on.

Doesn't need to be smooth, the plaster adhesive will sort out minor
variations. To be sure, you could always put some plaster dabs on the
wall and level those with a straightedge.
I've used screws before now, the advantage being you can adjust them in
and out indefinitely until you get everything level. At least then you
know which bits may need bigger blobs of adhesive.