Depends what the local rate is really,
The simplest answer is charge as much as you can
but I dont charge by the meter (unless its huge, to help )so its something someone else might give a more accurate answer on. The size of the area your cleaning will determine how much you should charge, the bigger the job the lower price per meter is the norm.
£3-4 per meter just for a clean on any reasonable sized area sounds expensive to me (or atleast should include the re-sand) but it will vary from area to area and how much you want the job.