I have visited this site several times in the last year and is relatively easy to find from the closest road if you have a GPS enabled OS map app for your phone, it is only 100m or so into the forest which is not as dark as it first seems (the map location of the cairn is very accurate despite it being in thick forest).
As previously noted the ground is usually very damp, so appropriate footwear is essential.
Many thanks for this.
Good effort Matt.
You're a better man than me for finding it.
Although in my defence I don't have GPS!