Hey Jack_k.
I think the answer depends on whether you actually know what your career ambitions are, and how solid your aspirations are as well.
If you are pretty solid on a specific pathway then the masters would be a great option. The MEng path is quite prestigious and definitely has an edge over BEng overseas, and academically would entail deeper and more exciting topics than what you can get with a BEng. Say if you want to pursue academia instead of going into the industry, the MEng gives you a better edge on applying overseas as well, so that's pretty cool. Doing BEng/CS is sufficient to start a PhD here, but not overseas.
The downside though is that you don't really have a flexibility of options to choose what you might want to do down the road, compared to doing BEng/CS. Personally, I think doing a BEng without an additional CS degree won't harm much anyways, the career prospects are similar with or without the CS degree (and you can definitely get software roles as easily as CS grads if you did either software or ECS engineering, if not it's still very much possible), but it does give you a perspective on what you want to pursue if you haven't already explored your options enough. Plus, I'm not sure if the MEng part of your degree is covered by CSP, so you might incur higher fees/HECS debt, and that's something to also consider as well.