Firstly, you have the legal right to wear the Kirpan at work.
It would be advisable to keep the Kirpan gupt and covered with a jumper, coat etc. If a member of staff asks you if you are wearing the Kirpan, then you can tell them that you do and show it with pride. All schools should be understanding because the 5 Ks are taught to students at school. However, other than that you don't need to tell anyone about the Kirpan as it doesn't interfere with your job.
A Sikh should wear the Kakkaars with confidence that if someone asks us about them, we remain calm, confident and comfortable that we have the legal right to wear them and that they are beautiful gifts from Guru Ji. Usually, students and staff get to know you as a person and later on realise you wear a Kirpan. By that time, they are comfortable with you wearing it because they see you for the person you are.
Hope that helps
ਸਤਿਗੁਰਬਚਨਕਮਾਵਣੇਸਚਾਏਹੁਵੀਚਾਰੁ॥