Hey there! Computer science at uni is actually a lot of theory and not that much programming, thats why unis require you to take mathematics A-levels as it really helps you with the theory part. Working in the industry though, a lot of times, don't require you to do anything remotely as deep as that. There are so many paths you could take in the field that you could pursue without good mathematics skills. (most commonly software engineering, web dev etc)
Considering that you won't be going to university, I feel that its important for you to develop your programming and computer knowledge and experience right now. Try to learn more from online courses (Coursera courses / CS50x on Edx etc), and/or experiment with some projects to get a good foundation. You can take advantage of the time others would have spent on uni, to work on your programming skills and build your portfolio early. (whether it be anything from simple websites, games, to automated bots)
You don't have to continue with A-levels since you are not applying to unis, however, I do recommend you to finish them as it's still good to have some formal certification of high-school education.
Regarding apprenticeships, I cannot speak from experience but there are a lot of companies out there. As long as you have a portfolio showing ambition, then there will be opportunities for you. LinkedIn is a great tool to build your network and find startups where you can get internships from. This will have to be after you are somewhat confident with your programming foundation skills though. In the early stages, you can probably find communities of your hobbies/interests on Discord, where you can meet friends and create programs for them to build your experience.
So if you really have an interest in programming and Linux over everything else, you should definitely pursue CS. Feel free to ask me more questions!