As there are such things as dangerous spiders, I don't think that fear of them is necessarily either frivolous or irrational. They can be very very still indeed then suddenly charge around like billy-o in a scary and unpredictable manner. The best way to relax about spiders in Britain is to become more familiar with them and recognise that even the biggest of 'em can do you far less damage than a wasp, horsefly or mosquito. Of course, if you live in a place where bad-guy spiders exist, you can get to recognise them. When I was in Oz I found one of those redback jobbies under a toilet seat. It didn't seem very interested in me, can't think why not.