The Attalos gas tanker is set to arrive at the Isle of Grain terminal in Kent.
It is believed to be the first cargo of liquified natural gas (LNG) sent from Australia to Europe in six years.
It is welcome news for many, as analysts expect the energy price cap to rise to £3,554 in October.
But No 10 insisted there was no risk to UK supplies and called for consumers not to panic.
Some of the gas from the Attalos is likely to be used in the UK straight away, but much of it will probably flow to Europe through the pipelines that connect Britain to the continent.
Some of it could return to Britain this winter – but there are concerns that shortages on the continent could jeopardise the supply of gas back to the UK.
These were played down by No 10, which highlighted both North Sea production and the use of “reliable partners” such as Norway in ensuring homes could be heated and the lights kept on over the winter.
The UK has some of the highest LNG import capacity in Europe, but it has very little gas storage.
Therefore, much of the LNG that comes to Europe this summer will arrive in British ports, but be shipped over to European storage sites.
A No 10 spokeswoman said: “Households, businesses and industry can be confident they will get the electricity and gas that they need over the winter.
“That’s because we have one of the most reliable and diverse energy systems in the world.
“These decisions, in terms of energy consumption, remain decisions for individuals.
“But what I’m saying is that households, businesses and industry can be confident that they will have the electricity and gas that they need.”
Ahead of Ofgem’s announcement of an increased energy cap, due on Friday, Chancellor Nadhim Zahawi will meet bosses from generating firms including Orsted, Newcleo and RWE to discuss what more the industry can do to ensure markets function effectively for consumers.
The Attalos departed from Malaysia on July 20, according to data from Vessel Finder.
It had picked up a shipment of gas that had come from Australia, according to commodity experts at Kpler.
The Attalos is expected to dock on Monday evening.
Because of the long distances involved, it is rare for Australian gas to find its way to Europe.
Most instead goes to countries in Asia.
But the deep gas crisis that Europe is currently facing has catapulted the need for new sources of the fossil fuel.
Gas prices have soared in the last year, and the UK price for delivery next month was up another 17 percent on Monday morning, hitting £5.40p per therm.
The energy price cap could rise to £3,554
Yui Mok
Chancellor Nadhim Zahawi
James Manning