Should I, a native speaker of Chinese and prospective student at Edinburgh University

, be able to change my chosen degree from MA Linguistics to MA Chinese and Linguistics?

Currently I'm 18 and am a British student of Chinese heritage - I studied English Literature, French, German and a linguistics-based EPQ for my A-Levels. I have an offer from the University of Edinburgh to study Linguistics for 2023 entry, and I love the look of the course in every single way, from how it's structured in each of the 4 years to the variety of subjects offered.

However, one thing that I had considered when choosing my degree when I was 17 last year was the possibility of doing a joint degree of Chinese and Linguistics, and it's something that, at this extremely late stage, I've started to consider again. For context, I grew up speaking Mandarin with my mother (who is, ironically, a Chinese teacher, but never found the time to teach me Mandarin) and I am able to hold a casual conversation very confidently, but I never learned to be able to read nor write, which I do consider a great shame. It is for this reason that I would really like to study Chinese to a proper native level, and also have the opportunity to study Chinese literature, culture, politics and history, especially because I would love to use my linguistic skills (including Chinese) in the future for things like translation, teaching, research etc.

So, at this stage, I have two questions:
1) Is it even possible for me to change my degree from a single to a joint one at this late stage?
2) How much would a joint degree with Chinese actually benefit me? Most universities in the UK outline the fact that their courses are 'unsuitable for native speakers', which appears to me as though I am not eligible for any of these courses.

I'm not sure if this is the best place for me to post this, so I'm sorry in advance if it's not right.