Hello,

You can easily complete your 12th class physics in 5 months.

First you complete all the basic formulas and derivations in the textbook which will appear for long answers.
Now you complete the short answer questions which are mainly concept based question.please try to learn concept here
It is good if you refer your textbook for good concepts.
This will help you a lot.

ALL THE BEST!!

Read and practice derivations and problems.
Most important aspect is that you need to understand concepts.
Don't try to mug up the theory.
Read, understand, practice... Is the key.