This looks to be an immature Steatoda nobilis (some striping around the legs, which become more of a red-brown as they mature).
If it bothers you, just put it outside. They are actually quite docile (the spider in your photo is in a defensive pose, as if it feels under threat...normally it would bolt for a hiding place, putting it's head somewhare dark - they often still leave their behinds visible, which can look a little comical) & their bite is not dangerous, nor deadly. Unpleasant perhaps, but very, very unlikely and the venom is no worse than a bee/wasp sting.
Females are home-bodies & generally stick to their web, close to a hiding place. Males can wander about, but are more seasonal. They are well established along the South coast & SE England...& before the recent press frenzy, largely went unnoticed.