Preparation for plastering

When having any re-plastering/skimming done it is important to remove everything that you can from the substrate. When your walls are skimmed they are basically being covered in water and water tends to lift anything that isn't secure, from the wall. What you might end up with is bubbles in the finish plaster where the wall paper has lifted from the substrate. I would try to get all the wall paper off if possible, without causing too much damage to the plasterboard. As was said before, when solid walls are skimmed a PVA solution is applied to the wall to equalise the substrate and reduce drying times and increase adhesion. Under normal circumstances, you wouldn't apply PVA to a plasterboard wall because it is designed to take a plaster finish, however where there is damage it is acceptable to do so. All but the most severe (i.e. holes through the plasterboard rathar than chunks where your scraper has slipped) damage should be filled in by the plasterer in the first coat, one the top coat goes on, you will never know they were there. At the end of the day, get a steamer and do your best, whatever you can't get off with a steamer probably wont come off when you plaster. Also, speak to your plasterer and see what he thinks it's always best to work together with your tradesmen!!

Ideally all paper needs to be removed use sugar soap and a scraper don't worry about taking chunks out the wall it can be made up. Never skim over wood chip paper or any other paper the moisture in the plaster will dampen the paper and with the weight of the plaster potentially cause it to fall away. Buy a heavy duty scraper from toolstation or screwfix they cost under £10 and use that to remove the main face and then sugar soap the rest.