Thanks to all of you for the comprehensive advice.
From various advice I've been given here and on CN (I've actually received some really great advice from current/past owners of my scope on there), and having a few extra days of visual observation of DSO's instead of just the moon and planets, I'm now starting to think I'd appreciate the wider FOV and longer ER of some of the other eps I've been recommended (in particular the ES68 24mm for wide-field and Meade 82º UWA 5.5mm for planets/high mag). I'm starting to realise the 4mm Celestron Omni plossl I have is 'uncomfortable' to say the least!
I've deliberately not rushed into buying anything, as much as it pains me to know I probably have another few days/weeks of little improvement (obviously excluding seeing conditions and darker skies) on the limited (but amazing!) objects I can see from my balcony currently (Moon, Jupiter, Saturn, Mars, Omega Centuri, Jewel box cluster, Southern Plaiedes et al). I've even let the classifieds go by without grabbing a discounted Nagler...(should I have?!)
I've actually built a light shroud for my scope today, so hoping that provides a modicum of improvement, although rather stupidly, I mistakenly let the foam touch the primary mirror when I collapsed the scope and it's left marks/potential scratches on the outer edges of the mirror, so I'm hoping that hasn't cancelled out the benefits of the shroud!

So annoying and one of those 'kick yourself' moments that is really hard to let go of, especially given the novelty of my scope (less than 4 months old). I've been furiously googling 'why I shouldn't clean my primary mirror due to scratches', to try to put a stop to the almost overwhelming desire to clean the mirror. Rookie mistake, I know, just hope the effect is almost indiscernible, as I'm led to believe from my searching. Would be sadly ironic if the shroud improvements are offset by the 'scratches' (I think/hope the foam has transferred something to the mirror, rather than actually removed the coating, but I'm not going to investigate further. Today at least! Is there an 'Alcoholics Anonymous' alternative for mirror condition OCD?!).
All that aside for the moment, I think I'd like to purchase a decent wide-field ep and one high mag one, both with good ER and wide FOV. As mentioned, I'd love to, easily, be able to purchase the ES and Meade described above. Does anyone have any sources for these, or if not, any analogous eps easily available in Aus? If higher-end eps in these focal ranges won't discernibly improve what I already have with my Super 25mm and Super 10mm, then please advise (although I find that hard to believe).
I know I should join a group and try out a few different eps, but currently, circumstances won't allow, so I'm having to do this somewhat 'blind', as it were. If there is anyone around Wollstonecraft/North Shore in Sydney that can lend me something, I'll gladly pop round!