What a mess.
Right - there are two legal 'systems' in the UK. One is criminal, which deals with punishing those who break the law, and the other is civil, which deals with putting people back in the position they would have been but for another's actions.
The rule of law is absolute. Dicey explains it best - you will not be punished if you have done nothing wrong, if you are harmed then the court will provide relief, and all of us are equal under the law. Feel free to look up Dicey and Rule of Law to confirm that. Note, I paraphrase.
Criminal law deals with punishment, and can involve the loss of liberties. As a result a defendant is presumed innocent until proven guilty beyond reasonable doubt. That proving is usually attempted by The Crown in the form of the CPS. Not 'beyond all doubt' and not 'with some doubt'. Many crimes (speeding is not one) involve a mental element, called a mens rea. You have to do the act, and you had to have a mental state while doing it. Theft, for example involves you being both dishonest and having an intent to permanently deprive. To help with this we have juries, who can use their world experience to decide what they think a defendant's mental processes were. Juries are directed by a judge and decide upon facts.
Civil law seeks to compensate someone for a loss. So in the theft case above if it was your cash that had been stolen you are now short of that cash. The criminal law does not care about you, it cares about punishment (government backed victim compensation schemes sit outside this). If you want your money back, you would need to bring a civil case against the perpetrator. Because civil cases tend to involve handing over money mistakes are less severe, and so you have to show your case on a balance of probabilities. Note the much lower burden of proof. Civil cases (bar defamation) have no juries, there is a judge only.
Judges make errors, as we all do. Judges often can think that a legal point is ill-defined. To help with this there is an appeal system, where a case can be reviewed by more senior judges. Typically in the UK the Court of Appeal has three judges (no jury, you need a majority verdict) and the Supreme Court has five (Brexit had all of the eligible judges, called the Law Lords).
For more information, a good and easy book to read is Howard, Nick. 2013., Beginning Constitutional Law. Routledge. I've found it free on Google Books for you -
https://books.google.co.uk/books?id=gAezmBsPrEoC&pg=PA1&source=gbs_toc_r&cad=3#v=onepage&q&f=false
I strongly suggest starting there rather than random youtube videos.