i have a sapele front door it is light weight and has a cork core is it fire rated 

Cork has good natural characteristics in terms of fire resistance so it may be that the doors were designed and manufactured as fire doors.  However, its not just the core materials and facings that have a bearing of fire resistance.  The installation of the door assembly (gaps, voids & alignment), the intumescent edge seals, the smoke seals, the door frame, the ironmongery & hardware, glazing and the fire-stopping around the assembly to the surrounding wall will also matter very much.

Therefore, it would be wise to engage a Competent Person to thoroughly inspect the door assembly and provide a fire door inspection report.  https://afdi.org.uk/category/find-a-fire-door-inspector/