I didn't know about them being illegal in the UK but certainly a good notion!
Yesterday, the wife and I were about to park and noticed a new-looking pickup truck parked across the whole side of the Handicapped pavement markings!
Not only could a car not park there but I have to wonder if the owner was actually aware of how crooked they had parked? Then again, perhaps that is their handicap! They failed the parking section of their Drivers Training test at school!!

While I don't think we have such a law or site for reporting such violations, it may eventually come to that!