Works can generally commence on site following the granting of planning permission however, the decision notice may include a number of conditions of development.
These conditions may include the provision of additional information before work can commence. This information would need to be discharged prior to any working starting onsite. In order to discharge these conditions you need to make a formal application for the Council to consider. Information on how to make a discharge of conditions application.
Once these conditions are discharged the Council will issue a revised decision notice that will outline the date when this condition was discharged and the corresponding application number.
Before work commences on site there may be other consents outside of planning that you will need to gain such as Building Control Regulations or the need for a bat licence from Natural Resources Wales.