Can teachers publish children's fiction books?

I am a secondary school teacher and I have written a short children's fiction book. I want to sell my book in school and give the proceeds to charity. My headteacher is very supportive, but I want to make sure I'm not doing anything wrong and wondered if there was anyone on this forum who either had experience or could could give me any advice.

I have aspirations of extending this to other schools in the area so they can raise money for their school too and I don't want to have any conflicts of interest and jeopordise my job!

Any suggestions and advice would be greatfully received.