would it be good idea for me to pursue LLB (3 years) course after my BA degrees and can I attempt for upsc exam in my LLB last year (3 year)?
It is a good idea to pursue a 3 year llb if you plan on pursuing UPSC you will also get an added advantage of completing graduation with BA which will help in your UPSC preparation, you will also get extra time this way to focus on your UPSC preparation.
Yes definitely it would be a good idea, as LLB is a very could course and you are planning for upsc then definitely your llb course would get you an edge over other during interview round if you clear the written, or still if you have the llb degree then also the career opportunities are quite good.
Hence it is a good idea.
I hope this helps