From the Foreign Office website on Australia. This is current as of today but things can and do change.
"From 18 April 2022, travellers do not require a pre-departure COVID-19 test to enter or transit Australia regardless of their COVID-19 vaccination status. You should check if COVID-19 testing requirements are different for any transit countries you will pass through on the way to Australia, or if your airline has additional requirements.
All travellers to Australia arriving by air, regardless of their vaccination status, must also complete a Digital Passenger Declaration (DPD). You can complete your DPD via the iOS app, the Android app, or the online form on the Department of Home Affairs website. You can start your DPD seven days before your flight and submit it within 72 hours prior to your departure for Australia. The DPD includes a declaration regarding your COVID-19 vaccination status and other health information. You may be asked to provide evidence you have completed your DPD when checking in for your flight to Australia. For further information, see the Department of Home Affairs website".
From the Queensland Government website
As an international arrival who has been outside of Australia in the last 7 days, you must:
take a COVID-19 test within 24 hours of arriving
travel as directly as practicable using a private vehicle, hire car, taxi, endorsed transport provider or ride share to a residence or accommodation (cabin on a cruise liner, boat or government-nominated accommodation) until a negative result is received.
Rapid Antigen Tests (RATs) endorsed by ATAGI (Australian Technical Advisory Group on Immunisation) are an acceptable form of COVID-19 test for international arrivals. A RAT can be undertaken at the airport after arriving. As such tests have to be endorsed by ATAGI (and they have an approved list of such tests) I would not carry a rapid antigen test kit from the UK.
Hopefully by the time you travel in July things will become a bit easier.