Woodlouse

Kalan, in the middle of the picture you can see a Woodlouse together with Sunburst Lichen (Xanthoria parietina)

@RafaeJS It is lichen.

You are both correct, the woodlouse appears to be feeding on the yellow lichen and there is also some grey lichen present. Hopefully an expert will tell you their names.
Three of the common British Woodlice are Haplophthalmus danicus, Porcellio scaber and Armadillidium nasatum, whether this is one of those I am not sure, hopefully an expert will advise you.

But it’s not lichen ☹️🙁