Hello,
I have tried my best to assist but please do double-check aspects raised with the reelvant authorities.
Firstly, you will need to determine the state you would like to be a Barrister in. Some Australian states have a 'fused' profession (i.e. admitted people are automatically Barrister and Solicitor) while some do not (i.e. admitted people have to choose between a Barrister OR a s Solicitor).
Thereafter, you will have to send your qualifications in for assessment. Depending on the State, there is either a Legal Admission Body or University who can assess your qualifications. You would be required to complete bridging courses with LLB/JD students - most UK applicants need to complete Australian Constitutional Law / Administrative Law. This would be assessed on a case by case basis.
Thereafter, if you have no experience, you would most probably be required to complete a 6 month Practical Training Program. Some States allow exemptions if you can demonstrate equivalent prior learning. Most PLT programs can be completed Online while you are in UK.
Finally, if you are looking at States with a fused profession - upon satisfying both the academic and practical experience component you will be admitted as a Barrister & Solicitor. In States where there is a split profession, you would probably be required to complete a short Bar Practice course.
I hope this assists - please do double-check the information I have provided - especially the last part (as I am trained as a Solicitor rather than Barrister).
Cheers,
G