Currently dry-lining my old cottage, rubble / masonry walls. For most
of the walls I am putting insulation against wall held in place by
stud-work. However I need to glue / fix 20 mm insulation board and
plaster board directly onto the uneven reveals, and my feeling is that
they are sufficiently uneven that I need to smooth them off, to offer
a good surface to accept insultion etc. to provice a good level
finish. I was going to render, but having never plastered I'm not sure
what bonding plaster is good for - would this be useful stuff to
smooth off surface and bond with the insulation board? Any advice out
there?

Cheers, Tom