So my speaking and writing skill is considered low, and i need some advice, BUT

Im indonesian and im obviously wasn't born with an english tounge, and that's not the saddest part, im in a boarding school
(Basically, you live in the same place as your school, here, electronic devices are super limited, so learning and speaking english is really hard (and rarely in my school the students speak english daily))
And i must get a minimum score of 8 in ielts, what should i do?
i've tried bringing english novels/ books, but still, my vocabularies are still not broad
Fortunately, in the class, the teacher often explain in english.
Sorry for any grammar mistakes here, im really thankful if someone give me some tips/advice

You seem to be in a bit of a pinch when it comes to developing your English speaking and writing skills. I would suggest that you try to join English clubs if those exist in your school, so that you can get exposure that you need and improve even in small ways. However, the best way to improve your skills would be to enter into an agreement with your school to allow you to spend some of your after school time with an IELTS tutor, either online or in person, who can help you improve your English skills in a targeted manner. That will help you properly improve your vocabulary and comprehension skills in relation to the scoring rubic for various testing sections in IELTS.

Hi, I also wasn't born with English and previously graduated from a boarding school. I feel the same way as you. Perhaps I can suggest you find other friends who have the same needs as you, who want to learn English and need to take the IELTS test. This could be a peer, senior, junior, or even your teacher. Then, you can create a schedule and agree on how to achieve your goals. And if your school doesn't have an English club or related activities, you can ask if they'll allow you to take additional courses because you need to improve your IELTS score. Good luck on your English and IELTS journey!