Good idea, but you ll need some knowledge of the business. I d suggest you do a bit of research to find out what existing security companies charge and for what service level agreement. Your Security personnel will need to be screened and have passed the relevant security City Guilds certification, if your staff work on railway stations/depots or sites they will need to hold a current track safety certificate. Good luck.
strong vetting and CRB police check. AIS ? licence