One such protest will entail a 19-foot-high orange balloon shaped like Trump as a baby, which London Mayor Sadiq Khan - who's feuded with the president - approved under "the right to peaceful protest".
The state visit has never been scheduled - there is fierce opposition to it in many quarters of Britain - and this trip is part of a working visit instead, meaning, among other things, that Trump will overnight at Winfield House, the US ambassador's handsome residence near Regents Park rather than in Buckingham Palace or Windsor Castle as a guest of the queen.
Asked about Trump's comments at a hastily-arranged meeting with journalists, May said she was delivering wishes of the British people.
Mr. Trump, however, suggested before leaving a North Atlantic Treaty Organisation summit in Brussels on Thursday to head for London, that Britons in general agree with his policies, in particular his tough stance on immigration.
May's future was thrown into question after two high-level cabinet members -including Foreign Secretary Boris Johnson- resigned amid the growing chaos surrounding Brexit negotiations.
On Friday, May and Trump will hold talks on Brexit, relations with Russian Federation and trade ties at the prime minister's Chequers country residence followed by a press conference.
South Korea airs worries over fallout from US-China trade war
The International Monetary Fund has warned that a full-blown trade war could undermine the broadest global upswing in years. High-level talks between the two countries starting in May had failed to deliver a breakthrough to head off a trade war.
But protests against Mr Trump have already started, with about a dozen activists from Stand Up to Racism Scotland staging a brief demo outside the Turnberry course on Wednesday. "That's certainly up to the people, not up to me", said Trump.
But the red carpet treatment is likely to be overshadowed by massive protests planned by Britons opposed to Trump's presence.
It explains that "numerous demonstrations" have been planned for President Trump's visit between July 12 and 14, with most of those in central London, and large crowds expected. "I think they like me a lot in the United Kingdom".
The two leaders will hold talks the following day at Chequers, the 16th-century manor house which is the prime minister's official country residence.
A small demonstration is expected to take place near Blenheim Palace in Oxfordshire on Thursday, the venue for Trump's black-tie dinner with May on Thursday evening.
Later, Trump will go to Windsor Castle for tea with 92-year-old Queen Elizabeth.