Hi! So hopefully this will still be relevant. I graduated this year from Asia Pacific Studies at The University of Central Lancashire. When I applied in 2017, I applied for Korean at 4 unis, including Sheffield, but was only allocated Uclan because of my grades. I did get a really good offer from Uclan though (96 ucas instead of 120) and even when my A levels went terribly, I was still offered a place on year 1 Tesol with Korean with 76 ucas points (DDE+D in extended project). I'm fairly certain the reason I was given so much leeway was because they really liked my application. Hopefully there's still some option to advertise yourself for uni applications (I heard they were scrapping personal statements), so these are my tips:
1) mention any historic interest in the subject. Self studying, relevant GCSEs, travelling abroad etc. I explained that I'd been interested in teaching English since my early teens and had been abroad so had a big interest in languages and cultures, and that I'd self studied multiple languages.
2) Go into detail about how your educational choices until this point have helped you decide on your course. I had chosen French and Spanish at GCSE and the combo of French, English Language and psychology with the intention of becoming an English teacher.
3) Focus on how your A levels are relevant. I mentioned language acquisition modules from eng lang and psych and how I used that in my personal life to help me develop my hobby language skills. Sociology is great for the cultural aspect too as Asian studies tends to be heavily social studies based.
4) mention that you know what the course entails. Asian studies courses are interdisciplinary so they're deceptively difficult. You have to balance the language element with history, politics and international relations, social studies and other things. In my final year of Asian studies we even did a whole module on sustainability. For Korean studies, you'll definitely have to explore history, but very likely Koreas relationship with other countries and their impact on a global stage. Mention how understanding Korea in context is super important because of current tensions in the Asia Pacific region. You don't have to know about it all, but express interest in understanding and acknowledgement of its importance.
5) perhaps mention career goals or intentions of further study if relevant, like doing research after graduation or teaching English in korea, and how the degree would be useful.
This is the basis of what I would do, so hopefully you can manage to get something concise. If you're going to have time next year to do some extra stuff, something simple like volunteering is fine but honestly don't worry too much. Focus in getting the grades they ask for. Maybe read some books about Korea if you're interested but honestly, you could even lie about that. Intense language study before the degree is only useful if you're aiming for the post-A level route which some unis offer, but is a waste of time and energy, so you should probably spend it on psychology.
If you have any questions about what my course was like, feel free to ask. I ended up taking Japanese and dropping it because personally I found it hard. I did study Korea and did a Korean class, and I also spent a lot of time with students in Korean studies, but generally our modules interlapped so I heard and saw a lot, and it wasn't too different from my own experience.