Regarding Facing Some Issue with Landlord

I am staying in a rental flat since 1.5 years. Ceiling leakage problem is happening since then and I too informed landlord in time. He worked on it. But still the problem wasn't resolved. Plaster is falling from ceiling all day since 20 days. Hence, I told him my decision about changing the house. But I mentioned the notice period of 15 days rather than 1 month. Because the problem is increasing day by day and my family is facing problems alot. Especially, my two years old puts it in the mouth. But landlord is not letting us leave before 1 month. But if I am having problems then I have a right to leave. As well as have read some where "A tenant has the right to a house that is fit to be lived in. Unsafe conditions, such as holes in the floor, plaster coming down from the ceiling, leakage, bad wiring, and the like are considered unfit. It is the landlord’s responsibility to see that the house meets the minimum standards of accommodation". is this correct? Kindly suggest. What can I do?