I don't know about great britain, but in America laws are thrown out if they're vague. There's a doctrine of vagueness. If it's not clear, it won't be allowed by the courts and the law will be considered null and void. See link.
I'm not in Great Britain, and our law is not the law of Great Britain. Just as in the US, when Canada was created we adopted the law of England but our law has evolved on its own in the 150+ years since.
In fact, the English law that Canada brought into our law was about 90 years more advanced than the version of English law that the US incorporated into its law, due to the relative ages of our two countries.
The link you site is entirely inapplicable, because it deals with Criminal law. Laws that impose a criminal standard are much, much, much more strictly construed, and where there is uncertainty, always construed in favour of the accused.
It is very important not to confuse the principles applied to Criminal law issues with the far more extensive and pervasive law concerning all the non Criminal law. Criminal law is a very small and narrow subset of the law which only involves issues between private individuals and the government/Crown in its historic role as the protector of the public peace.
In contrast, the government is rarely a party to a copyright law dispute, save and except the relatively rare situation where it happens to own or claim a private interest in a copyright, or has been involved in a breach of someone's copyright interests.
When it comes to disputes before them, Courts decide things. That is their role.
Some times they have to decide things based on principles, because one part of a statute implies one thing, while another implies something else, and, due to the peculiarities of the facts before them, no part of the statute is entirely and exactly on point. Courts aren't allowed to just throw up their hands and say to the litigants before them: "we can't figure it out - work it out between themselves".