As a permanent member of the UN Security Council, London wields veto power equal to Paris, Washington, Moscow and Beijing.
He will represent Queen Elizabeth II at the Church of Scotland's General Assembly from May 16 to 22.
The head of state's ceremonial approval of the withdrawal legislation allows Britain to leave its closest neighbours and trading partners.
The unelected upper House of Lords made some changes this week, including on the rights of EU citizens and child refugees after Brexit.
European Commission president Ursula von der Leyen said that Britain knows it has to align itself with single market rules if it wants to be close to it.
Britain's exit from the European Union should take effect at the end of this month.
The WTO's principle of most-favoured-nation treatment says countries cannot discriminate between trading partners.
The two sides have until the end of the year to secure an agreement.
The momentous day on which Johnson effectively won permission to abandon the European integration project was all but ignored in Thursday's media.
The Brexit deal covers separation issues such as EU citizens' rights and Britain's financial settlement.
Lawmakers begin debate on legislation to enshrine Johnson's divorce deal.
Boris Johnson will hold his first meeting with the new European Commission President, Ursula von der Leyen, in London on Wednesday.
The two sides will have just 11 months to settle that agreement following Britain's formal departure from the EU on January 31.
BoE governor, Mark Carney will handover on January 31 after six years in the role.
A final vote on Johnson's separation terms will come when lawmakers return from their Christmas break early next month.
Around 50 MPs, led by Mark Francois of the hardline anti-EU European Research Group, are backing the request.
Top of Johnson's to-do list is a bill to ratify the terms of Britain's exit from the European Union.
Britain is due to leave the European Union on January 31, but will remain in a transitional arrangement until the end of the year.
Queen Elizabeth II will open parliament in a lavish ceremony on Thursday.
Prime Minister Boris Johnson promised to "get Brexit done" by taking Britain out of the European Union by January 31.
The EU earlier imposed duties on imports of subsidised biodiesel from Indonesia.
The veteran socialist blamed the media for helping to cause his century-old party's worst finish since before World War II.