Thanks for the other suggestions, everyone.
Hilary - there's no way I could have slept in your bedroom knowing that thing was in there - somewhere
Sam - bought one of the plug-ins - thanks for the tip. I can't believe the blasted mosquitoes are still around. My neighbour popped in the other day for some help (he's blind) and when he went and wandered down our driveway in the sunshine it looked like a cloud was following him - it was mosquitoes

. Had to slam the door rather sharpish before they all realised I was standing there, mmm yum yum nice tasty Annie
I've seen the spider catchers like in Lakeland, but they're just not long enough. It would have to be 20ft long before I could even contemplate grabbing them.
DH sucks them up in the Dyson every now and then, but then has to go and empty it for me because if I saw one moving around in there I'd never hoover anywhere ever again (now, actually, that doesn't sound like too bad an idea

).
Marmite - yeeeeeuuuuuuk. But then, if it did stop them I'd consider anything. But the downside it that I'd be chucking up because of the Marmite smell
We too have three cats, but they've got bored by the big bruisers we get here. They just sit and watch them, probably laughing as to why their mistress is freaking out
Thanks everyone - I shall report back once I've started my therapy (probably only a three year wait on the good old NHS!).