Just removed a paper border from our girls room prior to repainting and in three places the skim coat has ‘blown’ away from the base coat. The holes are a maximum of 12″ diameter and the skim is about 3mm deep at a guess.

Can I use a normal filler to repair these or is there something that will be easier/better?

yes, normal filler, applied with a 10″ taping knife. 2 coats then sand.

Great…. what’s a taping knife? Just measured again and the diameters are 10-12″, still the same solution?

result…. looked in the shed and found an unopened box of plaster repair filler.
First coat on – cheers LB

once the first fill is dry, sand it down and refill, once that is dry fill again etc etc etc

Its all in the preparation to get a good finish.