@toomuchcardboard Pholcus phalangiodes commonly called the cellar spider though they've never been particularly fussed about where they live as long as its sheltered. They will eat even the big hairy giant house spiders. They are voracious and ambitious.
Ooh also, to avoid seeing spiders of the travelling sex starved nature - dangle a towel or bit of loo roll over bath sides. They slide in sometimes looking for Mrs Oh Go On Then If You must or sometimes distracted by the scent of water.. then can't get out (super shiny surfaces can sometimes thwart them).. Providing a wee ladder to escape means you're much less likely to be confronted by one when you hop in for a shower, and means the spider is much less likely to be confronted by a screamy naked human which I am sure they appreciate.
Spiders you're most likely to see in your house in the UK...
Pholcus phalangiodes - spindley creepy sods.
House spiders (Eratigena sp. there are several and tbh without a microscope and looking at their rude bits you can't tell and it doesn't matter as they all act the same anyway).
Amaurobius sp. Several of these two, small, stocky, dark. Harmless.
Steatoda sp. 'False Widows' - just an orb weaver, they've got a bad rap but its all rubbish. Very adept at catching wasps, they know how to avoid the sting, wait the wasp out whilst it knackers itself, they understand that both the bum and the front are dangerous ( a wasp could bite any of our native spiders in half in one bite!).
Zygiella x-notata, the missing sector orb weaver, so called as it misses a section out of its web for some unknown reason. However most will prefer the edges of windows if, like me, you are slovenly and don't wipe up webs. They are GREAT at catching annoying houseflies and craneflies that dink against windows. They make little sleeping bags against the window seal, laying out trip-wires, and then dash out when their Ring Doorbell system goes off, to see whats been delivered!
Drassodes sp. 'Stone spiders' (dunno why) small, mid brownish, have a rather frilly bum, large spinnerets for a small spider. Harmless as a fruit fly, unless you're a fruit fly.
If you're very lucky (or if phobic, unlucky) you may see a Mouse Spider, Scotophaeus blackwalli - not huge but pretty chonky and dark with a very furry satiny grey 'mouse' coloured bum. They do make me jump as they trigger the 'omg a tarantula' bit of the human brain before the 'don't be stupid its not even 50p sized' bit can kick in.
And in some places outside, as well as the very common Garden Spider (you know her, bum that would put J-Lo to shame, shades of dark brown to pale cream, lurking at face height in a huge web in your porch, setting off your Ring Doorbell) - you may have the Tube Web Spider, Segestria sp.
She's big, she's black, she's every halloween horror story spider... and she just wants to stay in her hideyhole and eat snacks that come trundling by. She's got metallic green chelicerae (the muscles you can see that drive her fangs, that you can't see) and out of her hidey hole she may panic and she looks a bit weird and 'THAT CAN'T BE NATIVE' ish... Don't poke her with a finger, she probably will bite you, but she'd really rather save that for dinner rather than defence.
We have a LOT of other spiders in the UK, many bigger or weirder looking, more colourful or possessing bigger fangs than this lot. Some are incredibly clever, with not just great eye sight and the ability to recognise faces (jumping spiders), but the ability to plan complicated routes (a cognitive ability that many dogs, horses, er, and even humans, struggle with!)...
None of them are medically significant - the risks with spider bites (which are very rare and cannot be identified as such unless you see the spider do it!) are actually infection from tiny puncture wounds that people don't notice much, or don't take seriously, and so don;t keep clean. Or very rare allergic reactions. You're at more risk from a mosquito or a wasp.
I find them endlessly fascinating but I can confess, if one is unexpectedly on me or runs up my duvet, it still makes me jump and I still have to work pretty hard at staying calm and removing them sensibly!