I have thought about it myself, but really don't think there's much risk. In Manchester weed is not seen as anything special & if you only get caught with personal use you only get a slap on the wrists.
If this was a site for "How to get kids hooked on crack" or something then I think they'd look a little closer. Of course don't be stupid and give out all your personal details on the net. Strange to say it, but there's a lot worse people on the internet than cops.