A Level English LiteratureWatch
People are going to tell you that A Level/ Advanced Higher is about delving into the material in a more sophisticated manner, about true understanding of the source material. Those people are wrong. What A Level is about, and I mean this absolutely literally, is learning to write a different type of essay (just compare a GCSE and an A Level mark scheme to one another), and, at least in the Scottish curriculum, learning how to cite and write a bibliography. Reading the reading list is probably a waste of time - you'll read it in class anyway, and more importantly than that, you'll be reading it the way the exam board want you to read it. If you read it on your own time beforehand, you're in danger of coming up with 'your own original ideas about the text' and other such heresies.
I don't mean to say that A Level/ Advanced Higher isn't hard work. You're going to spend a few miserable days before the exam rote learning the living daylights out of quotations, and a few miserable months before that submitting the exact same essay about the exact same topic (though with a differently phrased question) with continual tweaks, possibly up to a dozen times. I can actually only speak as one who has done the former, but I saw my classmates do the latter, and I can assure you it is no cup of tea.
If you do genuinely want to get a head start, I would suggest reading well-written literature. It can be from any place or time (though obviously it might help if you're doing a Victorian text if you've read some Victorian novels beforehand to get your head around the different vocabulary), but as long as it's what an English teacher would (arbitrarily) define as 'a classic', it will be of benefit to you, both in terms of improving your reading comprehension, as well as providing you with a greater pool of options when it comes time to write a dissertation (again, I'm assuming A Level is similar to AH in that respect). This will be particularly useful if you read several novels from the same movement, say, some Kerouac and Burroughs if you like the Beat Generation, or Woolf and Joyce if you're a fan of the Modernists. This is by no means mandatory, and I would encourage you to prioritise literature you enjoy over slogging your way through something you don't enjoy just to tick off another seminal text, but it will allow you to acquaint yourself more fully with both literary history as a whole and your chosen movement in particular.
TLDR: I wouldn't bother with this if I were you. Enjoy your summer while you still can.