This information can be found in the Plan General de Ordenación Urbana at the Town Hall. These plans are generally approved every four years and any interim changes must be publicly posted and approved, allowing affected property owners to contest or make a claim against the changes.
In many municipalities changes that have been made in the building codes and town plans, even though approved by the Town Hall, may need the final go-ahead from the regional government, which must vet and clear the municipal plans. In some cases, there are special building codes set up for specific zones. The “Plan General de Ordenación Urbana2 (PGOU) analysis is not for amateurs and needs a specialist to correctly understand it.
If your land is located on an existing and approved urbanisation, the permit will probably be forthcoming, however this must be verified. Care must be taken as some developments never received official approval and building has been stopped, as they never met the legal requirements for the services they have to provide, such as roads of a certain width, or water supply.