Yeah I feel like the biggest idiot in the world for not revising since day one, wish I could have gone back in time and kicked myself into gear! Nevermind! I'd say just get up the mark schemes and remember your equations, of course doing exam questions will help, but there's nearly always a good two pages of energy conversions if I remember correctly. Totally hate the electricity part of AS physics but, the resistivity formulas and god knows what will be mighty useful I imagine. I'm so screwed and wishing for a miracle.