The short answer: No, your UM would likely be denied access to FL - unless this was agreed to in advance by an appropriate person.
If you were wanting to resolve this in advance, you could contact the Platinum/CL Desk, or the FL directly (you should be able to find the lounge numbers with a quick search around here).
To my knowledge, there are no rules specific to the FL that I can find published anywhere. In this case, I would then defer to
QF's QP lounge rules which I understand to be applied across all lounges operated by QF - excepting those conditions relating to access which are incompatible with the type of lounge operated.
The following in the aforementioned lounge rules is stated regarding under 18's:
10.10 Children under the age of 18 years must be accompanied by an adult when visiting any lounge.
That's pretty clear cut, but as usual the lounges could exercise reasonable discresion as to if they enforce this rule or not.
However, they may also or alternatively rely on the following to prevent access to your UM:
10.6 Qantas Club staff have the discretion to refuse entry to any Member or guest at any time if, in their reasonable opinion, the Member has not or will not comply with these Terms and Conditions or the Club Rules, or the refusal is necessary or convenient for the orderly operation of the lounge or other facilities or the safety or comfort of other Members, their guests and staff.
I mention this because it brings into play the liquor licensing laws in which the FL is located and licensed. This question has come up previously in relation to another member in a similar situation, who was under the age of 18yrs, travelling in J and was also a paid member of the QP.
The advice I publish is a copy and paste from something I wrote outside of forum on the above scenario, and is in the Victorian context as that's where the aforementioned lounge was located. YMMV if the lounge is located in NSW, and you could easily research into that to see what rules apply to the FL there in respect of UMs.
In summary, depending on the time when the lounge is being accessed - 10.6 would not stand (at least in Victoria) if used as the reason to justify the denial of access by FL staff.
Now putting on my lay legal hat, we need to look at the Victorian Liquor license rules to determine if your presence there would disrupt the orderly operation of the lounge, in so far as if you had remained on premises would the liquor licensee be in breach of relevant laws, being Liquor Control Reform Act (Vic) 1998 (see
LIQUOR CONTROL REFORM ACT 1998).
In respect of the presence of young people on licensed premises, the Victorian Dept. of Justice states (
http://www.justice.vic.gov.au/wps/w...e+-+alcohol+-+young+people+and+the+liquor+law) that;
" Minors are allowed to remain on the premises of a business that holds a restaurant and cafe liquor licence and on-premises liquor licence with restaurant conditions. This is between the hours of:
7am and 11pm Monday to Saturday"
The act mentioned earlier covers this at Sect. 120, stating;
(1) If a person under the age of 18 years-
(a) is on licensed premises or any authorised premises; and
(b) is not-
(i) in the company of a responsible adult; or
(ii) on the premises for the purpose of partaking of a meal; or
(iii) in the case of a licence under which accommodation is provided, a
resident of those premises- the licensee or permittee is guilty of an
offence. Penalty: 60 penalty units."
We then have to look at the type of license granted to the facility in question (see
https://liquor.justice.vic.gov.au/ for Victorian license DB). Looking at the license (Licence No. 32286335), while the QP FL at MEL does not hold both a restaurant/cafe & on-premises liquor license, there is a specific approval/consent granted as part of their license, as follows:
Section 120 Persons under the age of 18 years are permitted on the licensed premises other than in the company of a responsible
adult during the trading hours but no later than 11 p.m. on any day.
So, given that there is a specific exemption/notation relating to S.120 in respect of the QP FL liquor license, the lounge is legally permitted to allow unaccompanied persons under the age of 18 years to remain within the lounge until 2300hrs.
! My son is a Qantas Platinum FF and I just wanted to know that if he is travelling without me (Platinum with CL) is he able to use the Qantas First? He is under 18 so the licensing may be an issue. 
