It would likely be India.
The shortest line between the UK and Australia is a great circle route across Europe, Turkey, Iraq, Iran, India, and Malaysia. From London to Darwin is about 8600 miles, with the halfway point somewhere on the Kathiawar peninsula of NW India, about midway between Jamnagar and Mumbai.
India
Greenland
Refueling points are normally halfway and include Singapore, Hong Kong and Dubai
Halfway between Manchester UK and Brisbane Australia is Xianshuigu, China
Gloucester, UK is halfway between Bath & Birmingham
There is no landing site halfway between the UK and Panama. That would be the Atlantic Ocean.
It was between UK and Argentina. It had nothing to do with Australia, and fortunately for once Australian politicians did not rush the country into it.
The UK.
The halfway point between London in England (United Kingdom) and Aylesbury in England (UK) is Watford. Watford is in England (UK).
What is the time difference between the UK and Australia
The UK has a population about three times greater than Australia.
Arnold, UK
Cheltenham
Most of Australia is desert, Not the UK. Australia has tropical forests, not the UK. Australia has masupials,not the UK. Australia is in the Southern hemisphere. Not the UK. Australia is a Continent Not the UK.