Keep an eye on the events section, there are multiple gatherings in and around the Sydney area that are friendly and safe
If it's a city or state park you can always check with their office/ranger in advance, although many parks close their gates at sunset.
EQ5/6 are proven mounts, personally I'd be reluctant to buy alternatives without researching their reputation. You'll want to look for a mount with a guide port, ST-4 compatible is the most common.