There should be an S1 thread around here, I'll see if I can find you and tag you on it, otherwise - you can always post
here, you can tag me if you'd like but there are plenty of other people keeping tabs on the thread.
Mostly: spam watch every examsolution video at 2x the speed, do two/three past papers then move on to a new module. 2 hours a day, every paper between June 2009 - June 2015. That's what worked for me, it might (and probably won't) work for you, so find something that you're comfortable with. I totally understand you re the sciences part; tbh I only
started learning U3 Physics three or four days before the exam, I don't quite have a solution there given that the same problem applied to me, sorry.