My school cancelled computer science. Is there a solution?Watch
(of course, Computer science at GCSE/Alevel is a plus, but it does not matter at all - literally)
Do well in maths (especially at alevel) and you can get any offer at any university and any sixth form. But of course do well - overall as well.
And, you’ve been learning programming in your own time - this’ll be very useful to put on your personal statement. But again, all you need is maths really and the minimum requirements.
Otherwise, most universities are quite relaxed about your background, as long as you've got at least some STEM background (and a B/6 in GCSE maths).
People joining the first year of a computer science degree at university often haven't studied it before nor written any code, so universities make the assumption that everyone is completely new to programming from the first lecture, nearly always teaching everything from basic principles (i.e. first week is "Hello world", learning basic input/output, writing programs using basic arithmetic, etc.)
Also, if you're still committed to software engineering as a career after you finish A-Levels, then you can earn a degree through apprenticeships instead - those are a really good option if you've got a strong programming background since employers care a lot more about your programming skills and a lot less about your qualifications compared with universities. - Universities look for people who are academically minded and able to study hard for exams, whereas apprenticeships are all about learning through real-world work experience, real projects, solving problems, etc - so the companies who hire apprentices place alot more importance on hiring people who can prove that they're able to write code and solve problems regardless of GCSEs or A-Levels.