Hi Samuel,
When I did English(General English) last year, I was really terrible at the start. I was not confident at all and was not good at writing essays. Also, I always took a long time to think and thus, took me hours just to write one single essay. However, by the end of the year, heading to the English Exam, I felt way more confident and was able to write quickly. There are a few reasons that got me to that position:
1. Knowing your texts
You need to have an indept knowledge of your texts if you really want to smash your SACS and Exam. Also, in doing so, it helps to think faster as well.
2. Planning
Try and plan as many prompts as possible for each text so then when you get the actual prompt, you straight away know how to answer it.
3. Untimed Essays
Before writing timed essays, what you first need to establish is how to write a decent essay first. Whenever, you finish an essay, you should always ask your teacher to mark it and what ever feedback the teacher gives you, take it on board and re-edit the essay and then show it again until you get at least 85-90% on it. That way, you know you are confident to write a great essay. By doing this to 4 to 5 prompts first, it will definitely benefit you.
4. Timed Essays
By doing the first 3 steps, it should help you when you eventually do timed essays. When starting timed essays, aim to do it within an hour and 5 minutes(with 15 minutes reading time). Then cut it to 1 hour(with 10 minutes reading time) and finally 50 minutes(with 5 minutes reading time). Even though the Exam is 3 hours, you will probably need 15 minutes altogether for the 3 sections to plan. Hence, by writing essays in 50 minutes(with 5 minutes reading time) early on, it will definitely help you in the long run and makes you less stressed out heading into the Exam.
Doing this approach really helped me in English, especially me being a below average English student in Year 11.
I hope my tips help.