It might be a bit early to tell what your study score would be, but the middle point is around 30 raw for English. There's a few factors that influence study score as well, such as how other students from different schools go, but seeing as though it's a selective school, you should be safe
For a very rough estimate, I'd say maybe 35ish, but you need to keep it up for the rest of Year 12, and score consistently well in your exam too.
My idea is not to think about it too much, and just do your best. If you keep worrying about study scores, you risk becoming anxious or too comfortable. And this is coming from someone who got an 18 raw for English Lang