Confused about new alevels and medicine applications

Hey guys,
I'm in year 12 and doing physics,chem,bio and maths and have been planning on doing medicine for 3-4 years now. But I'm confused about how the new linear a levels and medicine applications are working for 2017 entry.
The problem is that after doing internals (school exams) in bio,chem and physics and external exams in maths, I have realised that I need to drop physics as I'm not too great at physics and I totally messed up physic internal exams. I think realistically I would have to work very very hard to achieve an A in alevel physics and am currently at a B in year 12 but can possibly achieve A* on all the other subjects for alevels but I'm worried that under the new alevels doing only 3 subjects-bio,chem and maths would decrease the number of unis I can apply to for medicine and decrease my value as a candidate compared with someone who's done 4 and if most unis expect ppl to carry on revising material the AS stuff so you can do the As decoupled exam one year after you've dropped it and stopped learning it so you have an AS in a subject?? This seems highly unlikely to me but best to check!
Thing is I'd have no AS to show I'd even done physics as the subject is linear so would doing 3 be fine and dropping one around about now be okay and still stand a good chance of succeding for entry into medicine in 2017??
Thanks in advance and sorry about the rambling!! 😄