So I've been promoted to a management position

[Spadge Vernacular]

And no, that's not a sexual position and yeah, I can't quite understand how either but I've got to manage a load of people who are at least 1.5 times my age.

I work in the public sector, they're thoroughly decent people so I doubt they'll be voting Tory, so no need to put them all on immediate performance reviews.

What's the best way to prepare myself for this experience, any books or YouTube videos people recommend on leadership?

If this is a career move (long term) it might be worth considering some further education. The CMI have some bespoke modules that may be of interest and if you can get your employer to pay, an MBA is a useful.process. Such things won't just point you in the right direction, they'll get you "future-ready" for market developments.