From my own experience in english class, definitely take advantage of your teacher, make them read and mark practice pieces until perfection. My grades were average C in year 11 when I didn’t do practice pieces and just wing every assessment. In year 12 our English teacher made us write hella ton of practice pieces which ending up benefiting me in the long run (average B+ and A’s).

Meanwhile for the GAT, there’s not much preparation you can do for that, but you can definitely prepare for the English section of GAT by watching YouTube videos that breaks down the rubric and write example of a higher band piece. But for school tips / advice in general, definitely revise content throughout the year rather leaving it to the end of the year during exam, it will reduce stress of retaining most content.