need help asap

i'm 3 months into alevels and i still haven't started revising yet, does anyone know how to revise for essay subjects (i do health and social care)

You've named a single subject: "health and social care". Is that a single A level? Or perhaps something like a BTEC Extended Diploma (worth three A levels)?

If you're only three months in, then presumably you haven't learned an awful lot to revise yet. As with any subject (including essay-based subjects) you need to know the content. So make notes, flash cards, mind maps, or whatever works best for you, to learn the content. Then, as it's an essay-based subject, you'll need to write some essays to see whether you can get that knowledge down on paper in a coherent manner.

Are there past papers available? With mark schemes? Or, even better, exemplar essays?

Having said that, given that your only three months in, I'd focus on the raw knowledge right know and focus on the essays themselves a little later.