hey! i completed 3/4 hhd as a year 11 this year and it was one of my favourite subjects that i had accelerated in.
There is a lot of content for health but honestly very doable, in the summer holidays i would recommend starting content for the 1st sac coming up because its a short sac and by memorising definitions and learning a bit about how to structure your answers for the sacs is super important.
I also advise you to get lots feedback either by doing prac sacs or questions before each sac to really get a grasp of what your teacher and also the examiners are looking for.
Importantly you must know the content, health sac answers are very specific in terms of marks and you cannot wing it...
Overall i think you'll enjoy health (though it was killing me in unit 4) but i'm a bit biased since i really liked the subject throughout the year haha but lmk if you have any questions!! 🙂