Pumping at work

Mamas. I'm returning to work on April 10th, I'm a 6th Grade teacher in South Africa. Our state law says that I should get two 30min breaks to either breastfeed or pump at work. I want to go and speak to our Principal (Headmaster) today to ask about it, and also if I can have specific times set aside to pump.

I'm looking for advice for how to (ask for permission?) bring it up to her without sounding too aggressive. I almost feel as if I want to ask for the allotted times without bringing up the state law, as I'm not sure if she knows about it. I feel as if it may be best to ask first, see how she responds and then bring up the law if necessary as I'm hoping to get her permission without it. Does this make any sense?

Let's say she says she doesn't think its possible for me to have the extra time, and I should just use recess to pump. What would you say? How do I bring up the state law without sounding too hostile?