As someone who was in the same situation as u in yr11, all I can say is prepare for whats coming in yr12.
To put it simply, Yr11 english advanced is a breeze compared to yr12. Not trying to put u off or anything, but there is no handin for english advanced yr12 (okay idk about ur school but mine are all tests), and also the workload (not necessarily workload, its more pace) is a lot more/faster.
I'm not sure about u, but I'm someone who hated reading Shakespeare and texts, so at the start of yr12 I was really struggling on writing essays and handing them in for the teacher to check on time. However, once you do get a fully-fleshed out essay that you are confident in, it really becomes easy and depends on how much effort you want to put in. That is, you could always opt in for the classic method of memorising every essay (This is what I did for my trials) but if you are someone who wants more leniency/hates memorising (since trials you have to memorise roughly 4000), then doing some practice questions and seeing if you can rewrite the majority of your analysis is a good way of practicing.
Your pace at writing shouldn't be a primary worry, since if you did the correct preparation where you enter the exam with at least 3 foundation essays (analysis only) and 1 creative/discursive idea, you should be ready. Remember, you essentially have the entire yr12 to write 3 essays and 1 creative lol. For short answers however, if you were someone who wasn't strong at answering on the spot with no prior preparation, this might be difficult. But honestly you just bs in short answers anyway so its not even bad. U said u were doing pretty well in yr11, so I'm guessing you have an above average english comprehension. The only thing I would urge you to do is try to work on speed. There is definitely a time constraint on short answers section, and if you end up going over the designated time (45minutes), then you will fall short on finishing ur essay.
Ofc this is just general word of advice, because every school does english differently. I.e. our trials was last term and everything was tested. Meaning we had 1 less term to prepare than everyone else for the same test.