What are my chances?

This was completely accident and i am not ready for a child. 
​I had sex and my chances were 3%, we were using a condom and it broke.  He did finish inside me.  Im stressing out, my ovulation is tipped to be due (or start) in about 3 days, 4 if you count today.  
​Anyone know where i can get plan B or what to do? I live in australia. 
​I know this is entirely my fault and it was an idiotic move but i need help.
​When should i take my pregnancy test