Breastfeeding and returning to work soon

Au

I’ll be going back to work on December 2 and I will be pumping at work. My work place doesn’t have a place where I can pump and is usually extremely busy and I’m the only person working in the back. I need advice on how to ask for the space and time to pump once I return. I know legally they are supposed to have a place for me to pump and allow breaks for me, I just need to know how I should go about asking my boss for these things. (Our company has over 50 employees)