What is the best way to fix a hole too big for a bit of poly filler?
For a big hole, I cut a piece of plaster board, larger than the hole which will just fit through. A small screw put into the board will then help you to pull the plaster board back and with the help of glue (gripfill) fix it inside the hole. The hole will then be shallow and much easier to fill. Another useful tip is to mix a little PVA into your filler then when it dries you shouldn’t be left with the annoying periferal cracxks which you often get.