Can I pursue M.phil in English literature through part time basis as I am a govt. employee? Is the degree validated by UGC?

But, please, check beforehand. The UGC in the recent times have changed their regulations. Ph.D. has come to occupy an important place. A part - time pursuit is not allowed, these days. But, still, you can get a solution, after you get an admission. You can talk to the Head and seek his consent.

Yes, the degree is validated by UGC and you will get benefits of your degree in your government job too. All the best.