Got 3 D's in Year 12 END-OF-YEARS, and IDK what to do next

so i got 3 D's in my EOY's (Maths, Physics, Psychology) and my teachers have given me two choices:

1. I resit Year 12 (which is something I really don't want to do
2. I continue on into Year 13 and revise a LOT over summer, and really try and improve my grades as much as possible

I need at least a BBC to get into the uni course I want to study (Mechanical Engineering - Foundation Year @ University of Manchester) . I can also get a CCC to study Mechanical Engineering - Foundation Year @ University of Surrey, but I'm leaving Surrey as a "safe option".

Any advice on what I should do? Is it achievable to push my grades up, even though Year 13 Maths and Physics look like pure hell? What about clearing?

Any advice would be appreciated