Quitting During Probation: Do I Need a Relieving Letter and Notice Period Advice?

As I have received an offer to further my studies, I have decided to quit my job. Anyway, I am still in my probation period and have not received any confirmation letter yet. Will I need to get the relieving letter after I hand in the resignation letter? The company I work at is a very small company which does not have an HR department, so can anyone advise?

By the way, if the appointment letter does not state anything regarding resignation, is it still compulsory to give one month's notice? Or can I just submit an immediate resignation letter? I really need help and advice. I work almost 14 hours every day without overtime pay. :(

If the company is very small, you can directly talk to the plant head or the owner of the company. They can guide you!

Well, I have talked to the owner of the company. She didn't say any notice was required; just let her know the effective date of resignation. She seems very unhappy with that, and my colleague said she never gives a relieving letter. But I am wondering, what's the effect on me if I don't have the relieving letter? Will it be a problem when I want to apply for a new job after my studies?