thats a lot of work for the hsc considering ur gonna have to memorise at least 3 other pieces of writing and it might not be the most realistic. i had the same thought at the start of my hsc but once u actually finish trials u realise how much work it actually is. moreover, with 1984 especially, it lends it really nicely to be written about in a more chronological sense (i.e. the tripartite structure), so it might be good to consider doing that instead. in yr 12 at the higher level i think its less important to focus on themes but to focus on arguing your point/telling a story. for example the way that i know most people write about 1984 is talking about the initial oppression of winston, his rebellion, and then his eventual conformity to the party.
in this way, you are able to talk about every single theme possible basically, and you have quite a broad and adaptable essay. i.e. for his oppression, you can talk about the totalitarian state, power, surveillance etc. for his rebellion you can talk about love/sex/human instinct, and for his conformity you're able to talk about the human condition/individuality within a totalitarian regime. on the day, you can adapt your topic sentences/introduction to fit a certain theme better. also it is not certain that they will ask you to write about a specific theme, instead they could ask you a more syllabus key term related question.
the way that i wrote my essay was that i had a very broad central idea, but i looked at how it changed throughout his arc and i used it as a way to delve into all of the other things i talked about before. but most people i know just talked about the tripartite structure. this might not apply to ur school, but english ext teacher told us at the start of yr11 its better to write essays with a more chronological focus (what problem the text presents, and the ways in which its resolved in the text). its easier to talk about the authors didactic intent that way, which i find a common theme in a lot of higher graded essays
