The president and his wife Melania are due to arrive in Scotland on Friday evening after meeting the Queen at Windsor Castle.
More than 60,000 people have signed up to demonstrate in London on Friday when protesters intend to fly a large balloon over parliament portraying Trump as an orange, snarling baby.
Trump will spend Thursday night in London at Winfield House, the official residence of U.S. Ambassador to Britain Robert "Woody" Johnson.
Ignoring all diplomatic niceties, the convention-shredding United States president set up the four-day visit with a rebuke of May as she battles to stop her government falling apart over Brexit.
First lady Melania Trump disembarks after a flight with President Donald Trump. "I believe that the people in the UK, Scotland, Ireland, as you know I have property in Ireland, I have property all over, I think that those people they like me a lot and they agree with me on immigration", he said.
After London, he will travel to Scotland and then onto Helsinki to meet with Russian president Vladimir Putin. The president said on Tuesday, "I think they like me a lot in the United Kingdom".
One Facebook page advertising a London protest against Trump's first visit to Britain as president has around 60,000 people saying they will attend.
Trump's trip coincides with a tumultuous week for May after two senior ministers resigned in protest at her plans for trade with the European Union after Britain leaves next March.
Trump has clashed in the past with May - even though she is a conservative who shares his view that defense spending should be raised - and with her predecessor, David Cameron, who challenged Trump's anti-Muslim campaign stance as "divisive, stupid and wrong".
Mr Trump's planned visit has been met with plenty of anger, with 50,000 protesters expected to take to the streets of central London on Friday.
She listed Mr Trump's immigration policies, bans on some people entering the U.S., his foreign policies, and lack of support for taking action on climate change as having affects across the globe.
The prime minister will host him for dinner at Blenheim Palace, the ancestral home of Churchill near Oxford, and then for the meeting at the prime ministerial country retreat Chequers, north of London.
And Mr Trump raised the Cabinet resignations before heading to the United Kingdom for his long-awaited "working visit". The issue is 'Do they have freedom to protest, freedom to assemble and should they be allowed to do so?
Opposition MPS, backed by an online petition signed by almost 1.9 million people, called on May to cancel the state visit offered when she met Trump in Washington after his inauguration in January previous year.
The organisers behind the blimp however, said they were just "poking fun" and "hope Trump sees it".