Not sure the above is relevant. Is surface fog a legal cloud, anyway?
It's also wrong, although I don't have the books handy; a UK PPL can fly down to 3000m vis and down to the ICAO VMC of 1500m if he has an IMCR or IR.
All the stuff about a specific distance clear of cloud is silly; nobody can remember the rules, nobody enforces it and the distance is impossible to estimate.