Have a cold and I don't know what to do?

I'm in NSW Australia and in my town there hasn't been an active covid case in month's. I have a cold and so does my daughter, probably because I work in a daycare and she attends a different daycare, we're around lots of germs.

I have a specialist appointment tomorrow, the appointment was made for me and I was told that I have to attend because of some not good test results. It's Sunday, do I call tomorrow first thing and let them know I'm unwell or tell them when I arrive for the appointment (I call when we arrive and we don't enter the waiting room until it's my appointment)? There's no where I can get a mask from at this stage, I'm worried they'll push my appointment back because I need to be seen soon. I'm still expected to be at work so my daughter will still be attending daycare too.