Floodlighting your church building can be an effective mission activity and/or security improvement. You should consult your local planning authority who will be concerned to ensure that there is no detrimental effect to neighbours or traffic on adjoining roads. You will need to apply for a faculty for any new floodlighting installation and any significant work on existing systems.
Detailed advice: available from the Churchcare website. This includes a consideration of the rationale for floodlighting, local consultation and system design.