You have to check it with Local Planning Authority thoroughly to ensure if the classification of land i.e., mixed residential zone is correct or not. Local Planning Authority of Coimbatore functions under Directorate of Town and Country Planning, Government of Tamil Nadu. If it is correct as per the Local Planning Authority, then you can take planning permission and approval for building plan.
Planning Permission is the permission to be obtained under the Town and Country Planning Act 1971 before carrying out any development in the land/ building in both plan and non- plan areas. You have to apply to the concerned Local Planning Authority or Municipal Corporation or Town Panchayat or Village Panchayat, which would, based on the power delegated to them, either issue the planning permission themselves or refer to the office with jurisdiction for issue of planning permission.
Every development in plan areas, for which a master plan has been prepared, should conform to the zoning and in case development is not conforming to zonation reclassification will have to be obtained from the Government. The Planning Permission is valid for 3 years and it can be renewed for another period of 3 years on the application before one month of the expiry of the first permission.
Reference: Town and Country Planning Act, 1971