Marian cooke

We are a volunteer charity and own a oblong brick building. On one short end of the building there is an exterior fire door. It is metal in structure with the correct opening facilities. The other door is at the front of the building constructed of wood. At present the fire door is left wide open and the public use it as an access to the building. Could you give some guidance if there are any infringements being incurred such as should the fire door be alarmed ? Within the building there are internal fire doors, one open, one closed. My main concern is the open exterior door but also the security and our obligations to public safety from all types of occurrences such as (intruders, thieves etc.).