I would recommend security work need a license. Not sure how it works at Aus but in UK it's SIA License. 4 day course and 5th day exams so not a strenuous course at all.
Retail, Gatehouses, car park attendant, CCTV monitoring (separate license and training for CCTV) - can enhance on self employment with Security course. But to start off, Door Supervisor is usually the best n highly recommend.
Second, how about any usual jobs? Factory or independent shop assist / cafe? Simply try yer luck by walkng in the facility and enquire if they need workers. If they do... you may be in luck!