AOA

You can do it, nothing is impossible for a willing and determined heart.

If you can take leave, then take leave and start preparation otherwise quit the job and devout your time for preparation of exams. After taking exams, you can re-start/find new job or go for further degrees because after actual exams, its a time taking process till declaration of final result.

Good luck

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'Thee woh ik shakhs kay tasawar saay - abb woh ranayee khayal kahaan'