Hello JPJP; with respect, you seem under-informed re RAAF/Army Relations. There is comprehensive discussion thereof on this PPRuNe thread: http://www.pprune.org/military-aircr...history-2.htm. See my posts #16, 20, 31 in particular for some enlightenment.
It was always Army who decided which of their units would get Air Force air support and not the RAAF. Herewith self-explanatory extracts from post # 31 of that thread:
Before creation of a thinly-veiled unified ADF, the Army had multiple smallish units scattered all around the Sydney region in particular. The HQOC HOPS cell worked hand-in-glove with co-located HQ 1 GL Group which was the agency controlling utilisation of helicopter flying hours allocated for Army support and they decided which units would get support. The when bit was decided jointly to make cost-effective use of helo resources which had to be deployed to support Army units all around the nation, in the neighbouring archipelago and sometimes NZ.
When RAAF helos were assigned to support a particular unit, part of the tasking process involved HQ 1GL Group determining whether that unit could accommodate and feed the Air Force elements. Except for larger Army units and formations, the answer was mostly negative. Living accommodation was often limited and the Army rationing system was quite inflexible being rigidly based on numbers on unit strength. Where accommodation and catering was available at larger units/formations, it was generally availed.
Army did not then have the catering flexibility of Air Force and Navy with lesser staffing for that purpose and this also became a problem in some scenarios as feeding for flying elements often had to be at random hours to get the job done, so it was usually simpler to provide a degree of own rationing. As mentioned earlier, Air Force helo elements began enhancing field deployment capabilities post-Vietnam.
Regarding your Tiger comment. The primary activity for 9SQN during 2,000 days of Vietnam War operations was trooping for infantry battalions and they also did 900 days of gunship combat support compared with Army Aviation nil to date. I would argue an AAH designed principally for armour busting cannot adequately do the same intimate close air support job as more versatile utility platforms, like the Iroquois Bushranger, USMC UH-1Y Venom (Super Huey) and the US Army UH-60L DAP. There is good discussion re that on another thread.