B.A LLB

No, you need minimum of 45%. Do your graduation, and then do a 3 year law course.
There is an eligibility criterion set by Calcutta University for BA LLB e in which states that the student belonging to the general category must have percentage more than 45 in 12th in best of four subjects where is student belonging to SC ST category must have percentage above 40 to be eligible for further entry test
It will be an entrance test if you clear the eligibility criteria in which test for a particular task course will be there.
Another criterion is that the student must have completed its class 10th and class 12th between 2017-2019 in general category and for sc/st/pad for 2015-2019.
If you belong from the general category and your percentage are less than 45 you are not eligible for BA LLB from Calcutta University.

Common Law Admission Test CLAT is the best gateway for BA+LLB course. The eligibility criteria is given below.
1. Educational qualification : The candidate must have passed 10+2 or an equivalent exam from a recognised university or board with minimum 45% of aggregate marks (For general and OBC) and 40% for SC and ST.
2. Age limit: There is no upper age limit for appearing in CLAT 2020
Candidates who are appearing in qualifying exam in March/April 2020: Such candidates may also apply, subject to the condition they produce evidence of passing the qualifying exam at time of admission. The CLAT exam will be of total 200 marks with negative marking of 0.25 marks for every wrong answer. The all India rank below 1000 can be good enough for admission in NLUs in B.A. LL.B.Sc. LL.B. BBA LL.B.Com LL.B. And BSW LL.B. Course. So you have to obtain at least 120 marks for getting admission in the top NLUs.