Heya there
Having grown up in Australia where dangerous spiders are simply a fact of life im pretty much used to them however they are NOT allowed in my house.
My partner being a creatures-of -all-descriptions-lover refuses to kill them for me. So when hes not around I spray them til they are white. But be comforted in the fact that apparently the spiders in Switzerland are harmless ( small comfort I know but better than having a Sydney Funnelweb take up residence

)
As for buying spray to get rid of them , I found looking at the pictures to be the best way when my german was non-existant or even now when I have no idea what something is called. You should be able to find that sort or stuff in most larger supermarkets or if not try Jumbo ( a gardening- DIY superstore).
Hope this helps
Enjoy
kt