Loft insulation- mould

[helploft]

Hi, can anyone advise how much roughly it costs to deal with mould in loft insulation if you have had treated please? Interested in ball park figure if ok, as had interesting quotes, thanks!

What kind of insulation is it in?
Would it be more cost effective to remove and replace?

Interested in this- buying house and has mould on loft insulation but surveyor said it wasn't anything to worry about! Am inclined to douse a load of bleach over it myself and just keep an eye.