It looks like a female house spider, though the angle is hard to tell male/female, I see no sign of big pedipalps (they look like big boxing gloves on males).
That means she will stay with her web, she will wait for males to come to her, she will likely kill many that do, ditto other spiders that wander in and don't scarper quickly enough.
She won't come out of there unless disturbed, until she dies.
She is entirely harmless to you, but will eat woodlice, flies, wasps, other spiders, moths etc.
The UK does not have any medically significant spiders - though of course some people may have an allergic reaction to a bite, as people may do to any insect bite. Poor hygiene/minor wound care is another reason people have seemingly horrid reactions - people don't take tiny puncture wounds seriously.
Bites from spiders are far rarer than from many other insects, for several reasons.
They are reluctant to bite us unless fearing for their lives - we are too big to kill, they generally know this. We are not food. Their jaws are positioned in a way that makes it quite awkward to bite a large flat area of human flesh, and most bites are a result of a spider being squished up against someone, ie trapped in clothing.
Biting us is very 'expensive' for them, its a waste of venom which costs a lot to produce energy wise.