Parking offences were decriminalised (i think) in January 2007. That means the police now do not deal with parking issues - it falls to the local authority council to deal with.
As I work for housing in my local authority, I have to deal with numerous complaints about parking.
Unfortunately, there are very few rules to enforce. As has been mentioned, as long as you are road taxed, not causing an obstruction and not in a private (parking permit) zone, you can pretty much park how you like.
One note - apparently, it is a criminal offence to block a driveway with a car parked on it, and your car can be towed and impounded. It is not an offence to block an empty driveway.