thanx cleversod lol
the reason being is that the existing wall is plaster board only and a bit of a council mess up and with limited funding and limited expertise this seems the best option for us!
unless you could you suggest another way around a bad council job of a wall or would it be all together better to just rip out the old stuff and replace it with new boards (bearing in mind our level of experience and the possible problems that may follow with the joists or whatever) also! if we were to stick to our origional plan how long would it last ?!
If you are going to do this, suggest using Gripfix or similar adhesive. You are going to have to use tapered boards, then tape and fill the joints. Or use flat edged boards and have a plasterer skim the surface for you. But it begs the question, why not just get a plasterer to reskim the poor surface anyway.