Dont worry
it actually doesn't help with anything. You're not truly screwed until you let your worries consume your mind. Even if you don't manage to improve your english skills by then, worry + shit english skills = shit mark, calm + shit english skills = slightly less shit mark.
Try to find what the markers are looking for in each module, e.g. area of discovery = insightful understanding of the theme in relation to the question, module A = context etc. If your vocab isn't good (like mine) don't worry too much. My first priority is always to have a logical progression of ideas that answers the question. Then (or sometimes never) comes the sophistication and flair. Also -> read practice essays that received good marks. Before half yearlies my teacher passed around essays from last year's cohort, and although they were totally irrelevant in terms of texts, I just read through them to see things like how long, what they said in the intro, etc. and tried to mimic it as best as I could. My teacher also told me not to get too bogged down by creative writing, like srlsy it only counts for 15% of the hsc meh work on your essays first
Personally, last year I sucked shit at english (50-60% in half yearlies etc). This year, I've had some really good marks (full even) and other really mediocre marks (but still better than last year). I feel like these marks are luck-based to an extent but on the other hand I feel like constant average-good results isn't purely a fluke and maybe I'm slightly better??!?
Overall, no matter how shit your mark is, don't get knocked down and keep on trying different methods. You'll have setbacks and disappointments along the way, but what else can you do? Good luck ><
