Firstly this is not an ancestral property.
You have yourself mentioned that this property was your husband's grandfather's self acquired property, which was subsequently transferred to your father in law.
Now upon your father in law's intestate death, the share of your father in law devolved equally on all his own legal heirs.
Therefore the share of property acquired/inherited by your husband becomes his own and absolute property.
Your husband need not obtain permission form you nor anyone to dispose his own property.
If he has not paid maintenance to you after you started living separately away from him, then you are eligible for maintenance (provided you are not employed and do not have sufficient source of income to sustain your expenses), and for your child.
You can file a suit for injunction on any property that is still existing on your husband's name for the purpose of security towards the maintenance that may be granted by court in a maintenance case filed by you against him.
You may not be eligible to retrieve the properties that have been sold by your husband through court also.