Hello all. Have some questions regarding prepping and painting plasterboard for new wallpaper after removing old wallpaper. I came across some posts on here and other forums regarding a product called Zinsser Gardz. I was thinking of using this in the process as a sealer for any left over glue residue and hopefully to cut back on some laborious prep work. Scenario: My house is a new build and was a show home so it had a wallpapered wall in the lounge with mirrors and lights on it; I am getting rid of all and replacing with just wallpaper. The walls are plasterboard dot and dabbed over breeze block. There are quite a bit of screw sized holes in the wall where the mirrors were screwed to and 5 fifty-pence sized holes where wires were run for lighting... all of these holes are to be filled in. I have managed to remove the wallpaper, backing and most of the glue but it is quite difficult with plasterboard as you have to be delicate and not use too much water. I have experience with doing this to another wall that had a boarder. It was very laborious, involving many sessions of wet scrapes, sanding and washing of the area in-order to be able to paint. I am a bit reluctant with this wall due to the size and numerous holes in the plasterboard. The wall was originally skimmed then painted before the wallpaper was laid. The original coat of paint is thin and only served as a primer. Now my main question is regarding using Gardz. When should I apply the gardz, before or after filling the holes and sanding to an even surface? Or do I use it before and after? Also, what is the best paint to use before applying the wallpaper? Thanks for reading and for any advice you can provide.