hiiii

let me tell you one clear cut thing that if you want to get selected in a reputated government college then  you have to sacrifice your sleep and you have yo manage your valuable time like if you eat in 50 mints then you should try to eat the same food within 25-30 minutes then in rest of time either you can take a nap to energies your brain or you can revise your subjects.

if you are going to face your exam and you are not taking the coaching then you might face trouble during your entrence. but you have a option that you can drop a year for your entrance but 12th marks is important for participating in entrance minimum 60% should be in your marksheet for applying in entrance. I'll suggest you to focus in your school exam right now and then take a drop yaer and cllear your entrance.

best of luck aspirant.