This information is correct as of February 2016. www.gov.uk/government/world/australia
There are four categories.
School leaving Australian residents who are travelling on an Australian passport should be aware that the UK will introduce a National Health Service (NHS) surcharge, to be levied on all those applying for a visa to the UK (for more than 6 months’ duration). The level of this surcharge will be set between 150 – 200. (pounds sterling) per year of the visa’s validity.
An Ancestral visa has a validity of 5 years, so the surcharge is potentially 1000 (pounds sterling). “Tier 5 – Charity Worker” visa has a 1 year validity, the surcharge is 200 pounds sterling.