Hello!

As per latest rules, people who have not taken biology as a core subject for two years (11th and 12th) are not eligible to give NEET. So no, you are not eligible but keep yourself updated in case the rule changes.

This might help you-

https://medicine.careers360.com/articles/neet-eligibility-criteria

yes you can start preparing for neet , no issue you can also hire some coachig centre they will help you o prepare for you entrance as well as you can download latest sample papers and lat year question papers. all the best have a great future ahead.