The monarch will jet off to Sydney on October 18 before visiting the Australian capital Canberra.

He will then make a State Visit to Samoa in the south Pacific before attending the Commonwealth Heads of Government Meeting.

Charles, 75, will continue his cancer treatment right up until he flies, the Mail reports.

But the King’s doctors are reportedly happy for him to briefly stop his treatment while he is away.

Charles will start treatment again as soon as he gets back from his trip.

The King was diagnosed with an undisclosed form of cancer in February following prostate surgery.

His trip with Queen Camilla will involve up to ten engagements a day and only one rest day.

But sources said Charles’s doctors have helped plan the 30,000-mile trip.

The monarch’s entourage will include a travelling doctor, which is standard practice for royal trips.

It will be Charles’s first visit to a Commonwealth Realm since becoming King.

On Wednesday Charles hosted a reception at St James’ Palace to celebrate the Commonwealth Diaspora ahead of his visit.

He rubbed shoulders with celebs from around the Commonwealth like Cate Blanchett, Grace Jones and Motsi Mabuse.

Charles was said to be lively and took part in a traditional Siva Samoa dance.

He returned to Balmoral after the reception to rest up ahead of his trip.

Queen Camilla is also planning a break ahead of the gruelling trip Down Under.

The couple have reportedly spent their time at Balmoral enjoying long walks and foraging for mushrooms.