Nearly forgot if anyone can advise - the walls of "workshop" are stone/mortar and the interior walls are as expected "rough as a badgers a*se" - They are too uneven to batten and board, so I'm thinking the best method wil be to use plasterboard "adhesive" and plaster board, with an injection of expending foam to fill in the cavities behind (wiring is all going into trunking so not an issue). The bit I'm not sure about is the walls have zero damp proofing (old barn/stable), so do I need some kind of membrane or air gap behind to conrol damp penetration or some other method? Plasterboard these days can come with barriers or premeability built in from what I have seen.....

Cheers



Chris