Others have basically answered your question but I'll just add that very few specific actions are, per se, illegal under motoring laws.
For example, if you look for a law which specifically states that you can't drive on the 'wrong' side of the road, you won't find one. If the police see you doing it, they (together with the Crown Prosecution Service) would have to look through the list of general motoring offences (such as 'driving without due care and attention' or 'dangerous driving') and decide what the appropriate charge should be.
Similarly, reversing out of your drive isn't illegal per se but, under certain circumstances, the police (& CPS) might consider a charge such as 'driving without due consideration for other road users'.
As anyone who has ever read the Highway Code should know, the best practice is always to reverse into a drive, rather than out of it.
Chris