You have to give 3 months notice based on the employment contract. If after giving notice and you want to leave earlier you have to pay indemnity. Section 13 of the Employment Act quoted below is clear about it.
"13. Termination of contract without notice.
(1) Either party to a contract of service may terminate such contract of service without notice or, if notice has already been given in accordance with section 12, without waiting for the expiry of that notice, by paying to the other party an indemnity of a sum equal to the amount of wages which would have accrued to the employee during the term of such notice or during the unexpired term of such notice,"