You should not put house spiders outside, they will not survive.
The notion that garden spiders 'come in for a warm' at this time of year is not true.
What you see is house spiders, which have been born in your house and grown to maturity, looking for a mate. These spiders are used to warm conditions and will die quickly outside.
If you leave them, they will continue to roam around the house, unseen for 99% of the time.
When they slip into baths and basins, they can't get out - hence the myth that spiders climb up drains into houses. Aside from the fact that there is a 's' bend full of water in the way, spiders are far too fastidious to go anywhere near a dirty wet drain.
So leave old Boris alone - your experience was a rare one, and you get more benefit out of spiders in your house than by killing them.