From what you have posted, you should be able to get by with the mobile charger using the 15 amp plug if possible, which gives you 3kw
There are plenty of options for free AC charging in your area which will supply at least 11Kw, which is the max AC charging rate of the Model 3 - this will give you about 75Km of range per hour of charging
They are, Rouse Hill Town Centre (2 x 22Kw Tesla destination chargers), Stanhope Village Shopping Centre (2 Tesla 22Kw, 2 x Chargefox 22Kw Type 2 with tethered leads), Castle Towers Shopping Centre (3 x Tesla 22Kw)
All these will plug straight into the Model 3 with out any need for cables or adapters, so if you visit any of these for shopping just plug in while you are there