By Steve Holland

GLASGOW, Scotland (Reuters) - Most U.S. presidential candidates go abroad to sharpen their foreign policy credentials. Donald Trump arrives in Scotland on Friday to reopen a golf resort.

The presumptive Republican nominee, 70, visits his family's ancestral homeland to showcase his far-flung business empire. His mother was born on Scotland's Isle of Lewis.

With a throng of reporters watching, he will make a dramatic arrival by helicopter at his seaside Trump Turnberry resort. He has scheduled a news conference on the 9th hole at noon (7 a.m. ET/1100 GMT).

His visit to Turnberry, to be followed by a stop at his resort in Aberdeen on Saturday, will allow him to comment on the outcome of Britain's vote on Thursday on whether to remain in the European Union.

"I don't think opening a golf resort gets you many foreign policy chops," said Saul Anuzis, former chairman of the Michigan Republican Party. "But since he's there right in the middle of the EU vote, it may end up being a PR bonanza for him."

The risk is that the real-estate tycoon, who has yet to hold public office and rates unfavorably with 70 percent of Americans in an opinion poll, will make a foreign policy misstep at a time when Republican leaders are urging a more serious demeanor.

Trump has said he would be inclined to leave the EU. He has exchanged insults with British Prime Minister David Cameron, who has called the New Yorker's anti-immigrant policy ideas divisive and wrong. There are no plans for the two to meet.

'SCOTLAND HAS ALREADY BEEN WON'

His trip has baffled Republican officials who say he should concentrate on strengthening his campaign and taking the fight to the presumptive Democratic nominee, former U.S. Secretary of State Hillary Clinton, who is 68.

Trump defeated a crowded field of opponents for the Republican nomination but has faced one controversy after another, the latest over his firing of his campaign manager this week, a month before the party convention.

"His campaign has got all kinds of growing pains and it doesn’t make sense that he would spend any kind of time going out of the country," said David Yepsen, director of the Paul Simon Public Policy Institute at Southern Illinois University.

Turnberry is a storied course where the Open Championship has been staged four times. Trump invested $290 million in renovating the resort and golf course on Scotland's West Coast 85 km (53 miles) southwest of Glasgow.

He has portrayed his determination to build up courses in Turnberry and Aberdeen and overcome local opposition as an example of the type of leadership skills that Americans would get if he wins the White House on Nov. 8.

"Well, Scotland has already been won – and so will the United States," Trump wrote in a column for The Press and Journal newspaper in Aberdeen.

An Aberdeen family opposed to his development there has threatened to raise a Mexican flag as a reminder of his proposal to build a wall along the U.S. southern border to keep out immigrants who enter illegally.

The last Republican presidential nominee, former Massachusetts Governor Mitt Romney, in 2012 made a gaffe-filled campaign trip to London, Jerusalem and Poland.

(Reporting by Steve Holland; Editing by Howard Goller)