From midnight tonight, gay Christians can get married in the UK in a landmark move that will see thousands of ceremonies taking place across the country.
But about one in five British adults would reject an invitation to a same-sex wedding, research suggests.
A BBC Radio 5 live survey also found men were nearly twice as likely to spurn the nuptials as women.
The poll of 1,007 people found 68% agreed gay marriage should be permitted, with 26% opposing it.
And 22% of those polled by ComRes for the BBC, said they would spurn an invitation to attend a same-sex wedding ceremony.
A gay rights charity told the Huffington Post UK people's attitudes were "incredibly positive".
But Catholic Voices, which represents the Catholic Church, said the findings of the survey reflected the reality that people remained "deeply uncomfortable" with being honest about their true feelings on the meaning of marriage.
Ruth Hunt, the Acting Chief Executive, for lesbian, gay and bisexual charity, Stonewall, told Huff Post that the UK's first gay marriages were a "delightful" moment for the nation's history.
"The first same-sex weddings are a landmark moment in Britain and we’re delighted that so many people will be celebrating with happy couples up and down the country.
"These marriages will send a powerful signal to every young person growing up to be lesbian, gay or bisexual. You can be who you are, love who you love and achieve anything you want - regardless of your sexual orientation."
The comments come as the Church of England said it will provide no more resistance to gay marriage among churchgoers.
Last month, bishops attempted to ban clergy from marrying same-sex partners, provoking a backlash among Christian supporters of the change.
However, in a dramatic shift in tone, Archbishop Justin Welby told the Guardian today: "I think the Church has reacted by fully accepting that it’s the law, and should react on Saturday by continuing to demonstrate in word and action, the love of Christ for every human being."
But the BBC survey highlights how many in the UK are not so keen for change, with a substantial proportion of the population – 42% – disagreeing that gay marriages were no different from heterosexual marriages.