If you live in North Wales (or are having a blat around my way), check out
Arrive Alive. The nice folks there publish their planned mobile unit positions, however, they do state clearly, enforcement areas may change, without notice. Rule of thumb in my neck of the woods, don't do it, is it worth your licence? Mate of mine was followed for 3 miles by a blue & white V70 (idiot that he is, can tell how often he uses his mirrors). Needless to say, his 112mph average got him talking to a judge.
Anyway, whilst we're ignoring all politics that go with the issue, you might also want to check out
UK Speed Cameras.
Personally, I check the Arrive Alive site religiously, when I'm running late for work, it's worth those extra few minutes. Just don't tell Mr Plod
