Yeah!
Perfectly harmless. Spiders in the UK arent venomous save in extremely exceptional circumstances (the proverbial escaped pets and ones that came here on a bunch of banana), dont carry diseases and even if they did dont have any interest in human food, so arent a vector for them.
you say that but...!
when my band was on tour we played in Italy and our singer thought he'd twisted his ankle but a day later in belgium, some kids pointed out that it was a spider bite. his ankle was swollen up like it was broken, and he could barely walk on it. (although he did play the set). afterwards he went to hospital. They told him it must have been a wolf spider, as its the only spider in Italy that will give you trouble, and its also found in the UK.
how accurate that all is, i dunno, but its what he was told and im no david bellamy.
a friend of mine also got bitten on the shoulder once somewhere in europe and the spider bite melted a hole in his flesh the size of a 1p. thats how all the guys at the belgian show recognised our singers problem as a spider bite.