The Duke of Sussex is making the trip to the UK to attend his grandfather's funeral, but Meghan Markle -- who's pregnant with their second child -- did not receive medical clearance from her doctor to travel.

Harry will be following COVID-19 protocols for travel to and from the U.K. as well as during his time in his homeland, and the timing will work out for him to be at Prince Philip's funeral ... which will be held April 17 at Windsor Castle.

The funeral will be a family service closed to the public, and the Palace says Philip took part in planning it and asked for a private ceremony.

It goes without saying -- Prince Harry's return home will be very interesting ... as it will be his first face-to-face with the Royal Family since his and Meghan's bombshell TV interview with Oprah. Our sources say the Royal Family is not happy (understatement) with Meghan and Harry's interview, which some view as an attack and should have been handled privately.

It's also the first time Prince William's little brother will be back to see Queen Elizabeth II since he and Meghan stepped down as senior Royals in early 2020 and began their new lives in North America.  As you know, Harry and William are all but estranged, and the Oprah interview further drove a wedge between the two.

As we reported ... the Duke of Edinburgh, the Queen's husband of nearly 73 years, died Friday at Windsor Castle. His death came after some major health issues recently ... he was hospitalized back in February due to heart problems.