Hi Adam,
Being a Brisbanite transplanted to Ballarat I get home often enough to compare the skys. On the outskirts of Ballarat NELM is often around 4-4.5, on most clear nights away from the moon you will see the band of the Milky Way, and LMC/SMC and some other deep sky objects.. all naked eye.
In Brisbane suburbia you are probably luck to get much past a NELM of 2-2.5 with considerable light pollution making the sky look light and views of everything washed out. You will also have to deal with a thicker atmosphere from being near sea level, and suspended sea spray (especially if you are near the bay), not to mention all the lumpy air generated by a higher density of houses, roads etc..
The dark adaption your eyes will also be an issue. In my outer suburban back yard, which is across the road from state forest it is easy to find a relatively dark spot - This won't be the case in Brisbane with more neighbour’s lights, street lighting (both from your street and the one behind) and the generally more bright environment of the city. This will also limit what you can see, and limit how things that you do see appear in the eyepiece.
Certainly take the advice of others - check collimation, it makes a huge difference, wait for a moon free period and revisit from DSOs and see the difference it makes, and I'd say also stick to lower power - your 25mm plossl should give you more than pleasing views across a range of objects from the moon to brighter galaxies ... if you can find dark enough skys to see them
cheers,
Darren.