Hey Im going into year 11 too, if you are 20th century it's just a pure analytical subject, i did it in year 10, learn how to write the essays because they are different from standard english ones and have to be really straight forwad. Dates aren't important now, but know the key ones before anything major.
To be honest I didn't like it, simply because of the teacher, he was soooo slow, off topic and bias, studying at home was way easier, prevented me from doing revs and taking up specialist...which I'm glad, it's not too hard to get A's all year.
Over holidays just learn the basic concept of what happened in detail, so you can fully understand all factors leading up to events.
Good luck. :wave: