Hi and welcome,
If you live in the CFS areas then the answer is a probable Yes Depending on your brigade check out
www.fire-brigade.asn.au for more info on that.
If you are actually think of getting paid employment in fire fighting then it is pretty much a Full time career. Rather than a gap year job. in SA this would be with the SAMFS and i'll let others tell you about this.
Then there are DEH summer fir crews which are available and they tend to be from october to aprilish??? I think.
There are others on here who can tell you more detailed info but that is a general start.