Hello. I would really appreciate some advice please. I have a hole measuring about 14" x 12" running though an internal wall above a door. I was planning to fill this in with an old brick / cement and then plaster over both sides. I have a couple of questions please. (1) I had a plumber in doing some work and they said that I was making things hard, in their opinion a plasterer would wedge in a piece of plasterboard both sides and plaster over it. Does this sound correct, I could see this if I could get a batten screwed in but I can't as the hole is too small to get a drill in. Would it not be better bricked back up. (2). Could I just ask what plaster I should use to cover over the concrete to get a smooth finish for painting. I have filler but I am assuming there is a specific product I can get from Screwfix or something. Thank you.