After 12 th you should try to get into (BSc + MSc./ Integrated Msc) OR even in physics or even in engineering in case you are inclined towards it. For masters you can apply for institues like IIAP, IIST, AND TIFR .You can also do post doctrate in it .When you are done with your engineering courses you need to appear for national entrance exams . Some of are JEST , GATE . At present you should focous on your studies so that you can get admitted to pursue basic sciences.

hope this will be useful..