The prime minister and Foreign Minister Julie Bishop will spearhead Australia's presence at the Commonwealth Heads of Government Meeting in the UK this week.

But Mr Turnbull will also meet with German Chancellor Angela Merkel and European Commission President Jean-Claude Juncker in a bid to push ahead with a free trade agreement with the European Union.

The EU is Australia's second largest trading partner, third largest export destination, and second largest services export market.

It is also the only significant trading partner with which Australia has not launched FTA negotiations, but Mr Juncker said last year a deal with Australia is a priority.

"An FTA with the EU would give Australia access to a major market that's hungry for luxury products and the clean and green produce Australia is known for," Trade Minister Steve Ciobo told AAP ahead of the trip.

Australia exported more than $30 billion worth of goods and services to the EU in 2016/17.

Mr Turnbull will also join leaders and ministers from 53 Commonwealth countries in London to address the need for trade, investment and good governance, as well as cybersecurity issues.

Mr Turnbull said a meeting with British Prime Minister Theresa May came at a crucial time, following the chemical weapons attacks in Syria and against former Russian spy Sergei Skripal in the UK.

"We will discuss ongoing threats from terrorism, foreign interference and malicious cyber actors, as well as the uncertainty in the Korean Peninsula," he said in a statement.

Free trade agreement negotiations with the UK will start once it formally complete Brexit.

The prime minister will also hold separate meetings with NATO Secretary General Jens Stoltenberg before opening the Sir John Monash Centre at Villers Bretonneux with French Prime Minister Edouard Philippe.

Ms Bishop will meet with foreign ministers, including British Foreign Secretary Boris Johnson, to discuss issues including the recent use of a military grade nerve agent in an attempted assassination in Salisbury.

"Australia will be encouraging Commonwealth leaders to resist protectionism by making strong and practical statements in support of a free and open rules-based trading system," Ms Bishop said in a statement.

The minister will also address the Commonwealth Business Forum and participate in the Malaria Summit to discuss international efforts to combat malaria.

Australian Associated Press