To get started with your first games you'd just need:
1) The Core rules
2) Your Battletome for your army
3) A 5 second read of the point adjustments in the latest Generals Handbook from someone at the club who owns it.
And that's about it really. Getting started don't over-complicate matters for yourself. Your first games will be more learning the games core mechanics anyway; most of the errata and
FAQ and adjustments are only small modifications to the game rather than wholesale changes to how the core rules work. So leave them for when you're getting properly into the game and the info in them can easily slip into place rather than feeling like you're drowning in too much information.
For High Elves they were basically gutted in
AoS. There are a small number of their models that survive in the new Cities of Sigmar force. Where you could use them alongside other races within that book; or you could also use them as "counts as". For example High Elf Spearmen are gone, but there are still Dark Elf spear units in the book so you'd just counts-as for them.
The new "pointy Aelves" army we know utterly nothing on save that it seems
GW is going to potentially use them to restore high elf designs. This might mean that your HE army gets a full rebirth or only some units etc.... We'll really have to wait and find out.
Note for core rules this book
https://www.games-workshop.com/en-GB/Age-Of-Sigmar-Gaming-Book-EN-2019
Would be worth getting as it contains the core rules errata fixed up and also some of the Malign Sorcery rules which are pretty much default included in most play groups.
Note there are two expansions to the game:
Malign Sorcery
Forbidden Powers
Both add generic Endless Spells that pretty much any army with a wizard can use (only a couple of armies have no wizards - from memory its
KO and Khorne); the books in them also add a plethra of new things - as noted above the Malign Sorcery are more commonly used in most places, some bits of the Forbidden Powers are and aren't depending on the club. Both sets are still worth getting for their respective spell models.
After that the
GW website does have
FAQ and Errata for pretty much every book published by them. Like I said leave them to one side when you start things out. It's not really essential reading when you're still getting to grips with the flow of the game.