Right I've taken a closer look and although my pad is rubbing against the rim, it would appear that it is not because it needs adjusting. I have now found a broken spoke on my wheel which appears to have given me a wobbly wheel and that is why it is rubbing against the rim. A broken spoke is not a DIY job I presume?
I know someone who used to work in a bike shop and they always charged extra to work on dirty bikes. (They cleaned them first and charged for that.)Give the poor old bike a clean before you go - nothing demotivates a mechanic more than a filthy, ill-maintained bike.
+1It is for some people but probably not for you - not being funny by the way, but if you didn't know about the brake adjustment screw you probably won't know much about replacing spokes and truing wheels.
Zip down to your LBS for a swift (if they have the same type of spoke in stock) repair.