A grey foliose lichen, brown apothecia with thallose magins on twig.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
Having looked closer there's a possibility it could be Physcia stellaris but you'd need to check the medulla (inner layer of lobes, below cortex) to see whether it is K- (P.stellaris) or K+ yellow (P. aipolia). The cortex (outer layer) is K+ yellow for both.
Not sure from your photo whether there are pale pseudocyphellae present or not.
This is difficult. P. stellaris tends to have a more ulcerated surface away from the margins of the thallus (see on my own site), but not always so, as shown by Jenny's own photographs.
I am inclined to think this is P. stellaris, but the tests Jenny mentions are needed here.
Lat/Lng: 53.6, -2.5
OS grid ref: SD6920