I'm in NSW and was able to get it for free. Uni told me to get it, because I *could* (but unlikely) be exposed to whooping cough through working with kids when I do my pracs. I got the combination one that also includes diptheria and tetanus. I just went to my GP and asked for it and he had it there in the fridge and gave it to me on the spot, for free.

There not really too much information on the effects of the vaccine on your baby when you aare pregnant (i mention this because there are actually some vaccines you can get when pregnant in certain circumstances)... But do get it asap after baby is born if you are worried about not being immune to it. Its not a problem to get it when breastfeeding.

Whooping cough is very infectious, you can be infectious before you know you have it. There was a whooping cough outbreak last year within the day care my daughter goes to... she luckily didnt get sick - she's been immunised. However each of the kids there that got whooping cough werent immunised.