In answer to your original question, no you did not break the law. Tampering with a vehicle :-
“If, while a motor vehicle is on a road or on a parking place provided by a local authority, a person—
(a)gets on to the vehicle, or
(b)tampers with the brake or other part of its mechanism,
without lawful authority or reasonable cause he is guilty of an offence.”
so you would need to mess with the mechanics of the vehicle not just move it and the offense has the defense reasonable excuse which you would easily run.
The other relevant offense would be interfering with a motor vehicle which requires the intent to do another act such as steal when you interfere with the vehicle.So not relevant in your case.
Criminal Damage requires you to intend or be reckless about causing damage and you were not and indeed took steps to avoid doing so.
The only possible offense is TWOC, while i will happily get drawn in to a row with at least two coppers on here about legal issues of actus reus and mens rea in Twoc, the bottom line is in this case you did not use the vehicle as a vehicle merely moved it and there is a case that says moving a car round a corner as a prank was not a crime which clearly covers your scenario.
You can go to bed and sleep the sleep of an innocent.
I got bonus points off the wife for not getting drawn in to this earlier and taking her out for tea instead.(post hastily edited to hide stupidity)