What do I do if my computing teacher does not teach the subject properly? I'm a student in the UK, and I have a computer science lesson every two weeks. Most people would think computer science is my favourite subject, as I started coding from a very young age, but the computing teacher cannot teach it properly.

Firstly, she teaches things like copyright and made me spent a lesson researching a lawsuit between Ed Sheeran and Matt Cardle. She hasn't taught us a single programming language except a few lessons on small basic once, which there is obviously no need for, and she could have taught a modern language like python or JavaScript. We spend a month or so making magazine covers in Adobie's photoshop. We were recently doing “Should the internet be a human right?”, which isn't remotely useful. I have shown her the wikipedia page on computer science, and she says stuff like “Wikipedia is not credible” and “I know the syllabus better than you”.

Secondly, we had a test recently, and I answered all the questions correctly (to the best of my knowledge, and checked after), yet she marked many questions wrong, for example, one question was “Why may someone not be able to access the sites on the internet (Give 3 reasons)”, and 2 of mine were “Legal Restrictions (eg, article 13)” and “ISP may be blocking/slowing down the website (Due to the removal of net neutrality)”, and she marked both answers wrong. She also gives incorrect answers marks.

She also teaches things which are incorrect, like “This spam email is a spam email because it recommends using Firefox, which is an insecure browser”, and when I say it is not, she says it is because she doesn't like using it.

Is there anything I can do about this?
All of that is in the key-stage 3 syllabus (it is not all programming). However it may be that the teacher is over focused on one bit.
What is in the new computing syllabus
The new computing syllabus (post ICT), consists of three parts: Computer science, IT, and digital literacy. The timetabling people often make up name, so not wise to get to hung up about it.
You can download the syllabuses, here are some resources:

https://www.computingatschool.org.uk/data/uploads/ComputingCurric.pdf
https://www.computingatschool.org.uk/data/uploads/cas_secondary.pdf
https://www.computingatschool.org.uk/data/quick_start_secondary/progression_path.pdf

Where does copyright fit in
Within digital literacy there is a small section on, aspects of the law and ethics: copyright, patent, trademark, computer misuse, privacy, plagiarism sharing is caring, free software, etc; internet safety; evaluating resources (e.g. Wikipedia articles).
Copyright is a small part of the syllabus. Here is where copyright is mentioned (indirectly):
“They need to be aware of their legal and ethical responsibilities” — page 15 of https://www.computingatschool.org.uk/data/uploads/cas_secondary.pdf and “Explains and justifies how the use of technology impacts on society, from the perspective of social, economical, political, legal, ethical and moral issues” — last column grey section of https://www.computingatschool.org.uk/data/quick_start_secondary/progression_path.pdf
What to do next
Check to see if you teacher is only teaching part of the syllabus, then consider helping by sharing some of the resources below.
There are also a lot of teaching resources, here are a few.

https://csunplugged.org/en/
https://helloworld.raspberrypi.org/