A free trade deal with the European Union is set to be the top priority for the Prime Minister when she touches down in Europe for her biggest foreign policy test yet.

Jacinda Ardern departs this weekend for a European trade mission and to attend the Commonwealth Heads of Government Meeting (CHOGM) in London.

The trip is set to mark off a number of firsts for the Prime Minister; her first meetings with French President Emmanuel Macron, German Chancellor Angela Merkel and British Prime Minister Theresa May, whom Ardern has spoken to over the phone.

PHILIPPE WOJAZER French President Emmanuel Macron will host Ardern at formal talks in Paris.

The Prime Minister will also likely meet the Queen, who is the head of the Commonwealth and will attend CHOGM. And in a public "town hall" event in London, Ardern will join the stage with Canadian Prime Minister Justin Trudeau for a Q+A forum with a number of London youth, hosted by the city's Mayor Sadiq Khan.

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But beginning in Paris, Ardern will raise the free trade agreement with the European Union as a top priority in an hour-long bilateral discussion with Macron.

MORNING REPORT/RNZ Jacinda Ardern flies out from New Zealand today for her first official trip to Europe as Prime Minister. She's en route to the Commonwealth Heads of Government Meeting in London - but will also visit France and Germany. The trip comes as the European Union considers whether to push go on trade negotiations with New Zealand - something that could happen as soon as May.

France has been hesitant about a trade agreement with New Zealand, and agriculture is understood to be a large reason why.

Ardern is likely to use the successful negotiations of other trade agreements in competitive markets like China and the recently-signed 11-member Comprehensive and Progressive Trans-Pacific Partnership agreement as examples of how issues in agriculture are dealt with at the negotiation table.

The FTA would represent about $15 billion in two-way trade, but a mandate for the EU to begin negotiations is yet to be voted on by the 23 member states. It is expected to be considered in May.

CARSTEN KOALL/GETTY IMAGES Ardern will also travel to Berlin for talks with German Chancellor Angela Merkel.

Germany however - which along with France, holds significant sway in the EU - has been publicly supportive of a deal with New Zealand. Issues of reciprocal education agreements, and visa access are likely to be one priority in Ardern's discussions with Merkel.

Ardern will then have a formal discussion with British Prime Minister May at 10 Downing St, ahead of the opening of CHOGM, and a free trade agreement with the UK following its exit from the EU will be a priority.

While the UK has been given the green light to begin talking with other countries on trade, no formal negotiations can begin until the terms of its exit from the EU have been finalised - not due to occur until the Brexit deadline of March 2019.

CARL COURT/GETTY IMAGES Britain's Prime Minister Theresa May will host Ardern at 10 Downing Street for talks.

Her trip however, coincides with a number global flashpoints that will shape the tone of her meetings with all leaders, not least the recent chemical attack on a Russian double agent on British soil, largely acknowledged to be the work of the Russian Government.

New Zealand had raised international eyebrows over the reluctance of Foreign Minister Winston Peters to relinquish efforts to reignite free trade talks with Russia, in light of the chemical attack at Salisbury. He will also be travelling to Europe and is set to hold talks with UK counterpart Boris Johnson.

Both Ardern and Peters had already made strong statements that New Zealand stood firm with Britain in the face of the attack, which put the agent, his daughter and more than 20 other civilians in hospital in serious conditions. But it's likely Peters' visit in particular will include some damage control and both will likely give further assurances that New Zealand's position had not changed.

Climate change will be a priority discussion with all leaders, and within the Commonwealth 31 of its members were small island developing states, most acutely affected by the effects of rising temperatures.

Meanwhile recent reports of alleged plans by China to set up a military base in Vanuatu is likely to be an area of common ground between Ardern and Macron.

France is a Pacific nation with territories and strong interests in the region. Where New Zealand and French interests have not always historically aligned in the Pacific, a staunch opposition to the militarisation of the region will be held by both countries.