Hi! Firstly, take a deep breath. Clear your mind and understand that many- and i mean MANY- people will be in your position, or a similar one right now. You're reeling from your grades and feeling burnt out (reasonably so, the jump from GCSE to A-level is not an easy one), and the year 12 january mocks feel like the end of the world, but they are definitely not.
The bad news first, on your point about predicted grades: the harsh reality is, you are extremely unlikely to get predicted an A in physics or biology. Your teachers can only work off the evidence they're given, and if your predicted grades are to come out before your AS grades (they did for me in my school... although it may be different for you), then your chances of being predicted B+ are slim. This is not for certain, just the likely reality. If you're applying to university and have high aspirations, perhaps consider taking a gap year? I'm not sure how feasible this would be, but can open up a lot more doors if you pull it out the bag in the final exams.
The slightly better news, about your AS grades: you still have three months. Biology is a heavily content-based subject, and therefore I believe with the right amount of effort, you can pull it up to at least a C/B within three months. Emphasis on "right amount of effort". Nobody can tell you how many hours to study, because nobody knows how well you are at memorising/learning except yourself, and you need to be honest with yourself. I can't recommend enough using flashcards- which you can make on stuff like quizlet if you dislike paper- and gathering your notes from PMT should be enough for AS. Furthermore, the AS grades like genuinely, are not as important as certain colleges make them seem. I was told at some universities that unless they're good, they're straight-up ignored. (As an example, I got a C in AS maths before I dropped it. I currently have offers from Glasgow and Durham for Law. They didn't look at my AS grade and go "oh my god it's the end of the world".)
Maybe you can get As at AS, only you and the exam paper can decide that really. There's a lot of youtube videos that can give you much better advice on *how* to *actually* study than TSR threads can. If you're worried about the final A Levels I can assure you, if you start soon, you will be in a very strong position to get As, despite your low mocks grades. If I was in your position I'd take a gap year and apply with my final grades if my predicteds and AS might not be great- but of course, that's up to you entirely.
Good luck!