Price to plaster over old artex?

Its very hard to price over internet as there are many types of artex finishes which may or may not be able to plaster over and would required to be seen.

for a 4 by 4 metre its around 240 including materials

Plasterers will not price per square metre it will be priced for time to do and materials, so will need to scrape Artex, PVA and then Skim and cost will also be on size of ceiling to be completed and how many lights need to be removed to allow skim

Plastering over artex is same price as normal skimming £21/£25 m2 this is for standard artex shape and low stiple. If you have a uneven pattern or high stiple the cost be more as the artex need to tested and removed