With growth shrinking and the government riven over Brexit, Saturday's wedding is set to provide a national boost and give people an excuse to party.
Around 100,000 people are expected to pack the streets of Windsor, west of London, to join in the festive atmosphere and get a glimpse of the newlyweds' carriage winding through the town.
Some 2,640 people have been invited inside the Windsor Castle grounds for a closer look -- among them Rashid Bhayat.
"It certainly could be a moment of national unity. It is a real opportunity for the country to celebrate," the youth inclusion charity chief told AFP.
The wedding in St George's Chapel at Windsor Castle brings together Queen Elizabeth II's grandson, who is sixth in line to the throne, and US former actress Markle, who at 36 is three years his senior.
The dress and the wedding rings are a closely-guarded secret, as is Harry's uniform and whether he will be given a new title.
The service starts at midday (1100 GMT), with the newlyweds emerging to pose on the chapel steps at 1:00pm (1200 GMT) before a 25-minute carriage ride through Windsor town.
Queen Elizabeth is then giving a reception for the 600 guests in the castle's St. George's Hall.
In the evening, Harry's father Prince Charles, the heir to the throne, is hosting a private reception for 200 family and close friends at nearby Frogmore House.
- Fun and surprises -
"Even the palace are promising fun and surprises so hopefully we're all going to have a big smile on our face and we'll be toasting this royal romance of the year," royal biographer Andrew Morton, told AFP.
"What you're going to see is the symbolic union of the special relationship, of America and Britain."
The same cannot be said of Markle's own family.
Her older half-brother Tom and half-sister Samantha have not been invited.
Tom wrote an extraordinary open letter to Harry on April 26, saying TV fame had made his half-sister a "jaded, shallow, conceited woman that will make a joke of you".
Politicians are also off the guest list, so US President Donald Trump and British Prime Minister Theresa May will not be attending.
It will be a chance for the British public to leave behind temporarily the deep divisions that have emerged over Britain's future outside the European Union.
It could also bring a welcome boost to the economy.
The British economy grew at 0.1 percent in the first quarter of 2018, its slowest pace in more than five years, and the Bank of England has slashed its growth forecasts.
The Brand Finance valuation consultancy estimates the wedding will contribute £1 billion ($1.35 billion, 1.15 billion euros) to the British economy this year.
That includes £300 million in tourism, £300 million in advertising value for the UK and £250 million in retail and food spending.
- Party time -
The royal wedding commemorative china has already gone on sale, while stamps and a special £5 coin have been issued featuring the couple.
Besides the official souvenirs, Windsor shops are stuffed with mugs, bookmarks, tea towels, postcards, British flags, face masks and cardboard cut-outs as the town cashes in on its big day.
Traditional street parties will be held around the kingdom.
Market research firm Mintel, which surveyed 2,000 people online, reported that a third of Britons said the wedding made them feel more proud to be British.
"Where stories about negativity and uncertainty dominate the headlines, it's heartwarming that the fairytale story of a glamorous Californian actress marrying her British prince has captured the public's imagination," said Mintel analyst Jack Duckett.
The last time a US divorcee married into the British royal family, king Edward VIII had to give up his throne. The name Wallis Simpson and 1936 still send shivers through Buckingham Palace.
That Markle, a biracial, divorced US TV star, is being welcomed with open arms is a sign of how Britain has changed since.
"Britain is a very multicultural society. It was not the case of the royal family until now, but Meghan Markle brings a whole new kind of dynamic," said Bhayat.