Application to come late in school

Please correct this letter, I wrote this to principal to grant me a concession for late entry at school due to pregnancy, and please make changes if required.

Dear sir

This is to inform you that, I Bijoya Sutradhar hold the position of a teacher in your school requesting you to allow me to come in school a little late due to pregnancy, as sometimes it takes a little longer to get ready than usual. regarding my work, I assure you that I will never let it affect my tasks in the school.
So kindly grant me a concession for my late entry in school I would like to thank you in advance regarding this matter.