If you know the concepts then it is easy to prepare for Physics in 45 days.

Take help of NCERT books. Complete all the exercises they are very important. Sometimes, you can get direct questions as well.

Give importance to the topics which carries more weightage in the exam. You can also solve MCQs related to them.

Refer past year problems fo your practice and it is recommended to solve test series to analyze your preparation level. So, you can work on your strength and weakness and you can increase your speed as well

You should learn all the formulaes and you should learn the technique to use them.

All the best for your preparation and exam!!