With same-sex unions now becoming the norm in the UK, Mary Russellgets ready for her daughter's big day tomorrow

By the time you read this, I will have a new daughter-in-law - Trace - and by tomorrow, she will have wed my daughter twice over.

It all goes back to last Christmas morning when Trace popped the question - for the fifth and absolutely the last time, she said firmly. The tactic worked: Freya accepted, the plans were set in motion and the wedding takes place this weekend in London.

Though it's nearly two years since the law in the UK made it possible for same-sex couples to legalise their relationship, the idea is still relatively new.

Take the language. Although we're all calling it a wedding, the legal term is "civil partnership" and the whole event, spread over two days, takes place in two stages, with one part happening in the local registry office and the main part - the exchange of rings, the champagne, the speeches and the non-stop party bit - in the couple's garden. They'd have preferred to have the entire thing done there, but their garden is not a "licensed civil partnership venue."

And because they want some shape to the ceremony they've got a celebrant coming who will guide everyone through the whole thing. (The celebrant's other job is to do a Health and Safety check on the house and garden.)

There's no aisle, but there's still the walk through the French windows across the grass and into the marquee - both dressed, of course, in all their finery. Each has confided in me as to what they are wearing and, although I'm not allowed to reveal details, suffice to say that both have, independently, chosen a colour not usually associated with weddings. And one at least will be wearing an outfit designed by someone whose name begins with the big A.

"Yes, I'm going to be the label queen," announced Trace. Although there is one small problem: she's not looking forward to having to proceed down the aisle.

"That's what I can't bear," she wailed. "Everyone will be looking at me." "No they won't," said Freya soothingly. "They'll all be looking at me." (That's my girl.) So, while Freya explained the running order to me, Trace sat out on the back doorstep, chain-smoking her roll-ups and feverishly working her palmtop game console.

"What's the matter out there?" I whispered. "Nerves," said Freya.

Nervous? Trace? Who whizzes round the kitchen in helmet, mouthguard and scarlet boxing gloves practising her hand chops and high kicks. "I'm not nervous," she said. "But I thought we'd just do the business and then have a bit of a barbie in the back yard." An Australian-Aboriginal, Trace believes that no party - wedding or otherwise - is complete without its barbie, and so, yes, they're having three. And a fire pit.

A lot of planning has gone into this. Trace took on the job of finding a celebrant, but the first website she contacted answered her phone call with a sort of drawn-out "helloooo", which she found offensively English in some unexplained way, so she took her business elsewhere. Message: don't mess with Aussies if your accent doesn't fit.

Freya's job was to sort out the backroom team. In fact, the sisterhood has rowed in from all directions. One friend, who cooks for the House of Commons, is doing the food. Two others are doing the sound system and the lights. Others are providing spare beds. And not just the women. A former boyfriend of Freya's - from the old days - is running an unofficial taxi service.

BUT THERE'S STILL the nitty-gritty. Can they get everyone into the marquee for a prompt 4pm start? Freya's brother, arriving as a surprise from Australia, has already been given this task. But how will people know the plan of the day since few, if any, have been to a civil-partnership ceremony? Easy: on arrival, each guest will be given a welcoming card telling them exactly what's happening and when.

Will there be vows? Yes. Both Freya and Trace have written their own, and I know when they speak them to each other - that will be my damp tissue moment.

Choosing a reading required considerable research, since most on offer refer to heterosexual weddings. And they were all naff anyway, hetero or not, Freya reported.

Will there be music? Yes. When the celebrant gives me the nod, I have to pick up my sax and hit them with She Moved Through the Fair.

No two weddings are the same, of course. In my own case, we met, fell in love, Ian proposed on the stroke of midnight one New Year's Eve and within six weeks we were married. He invested in a new shirt for the event but not a new suit - though he did splash out on a new one six months later when he was best man at someone else's wedding. Then, the night before the wedding, he lost the ring and the cheque I wrote for the celebratory drink bounced a week later.

My son's wedding in Australia was a red-carpet do with the couple's baby daughter as the guest of honour. My younger daughter, working as a sailor around the Caribbean, called one day to tell me she'd got married: "Darling, married? Where?" I asked, thinking Barbados, Miami, New York maybe, "Down by the railway station at Fort Lauderdale," she replied.

Of course, the inevitable question is: why do it? Both Freya and Trace, independently, gave the same answer: "Because now we can." As simple as that, a celebration of equality.

But it's still worth recalling that gay and lesbian people have had to conceal their love for each other for centuries and have been marginalised and isolated as a result, as indeed many still are.

AS I WRITE this, the press carries a story about a US Senator being hounded for his alleged homosexuality and another story which records the extent to which gay men in Zimbabwe are persecuted.

Here at least, the time has come and people are ready. "Do I hear wedding bells ringing?" the florist asked Trace, and didn't bat an eye on learning yes but that there was no groom involved. Both workplaces have received the news with equanimity, and one is even giving a celebratory office party for the bride - and her bride.

Myself, I'm simply happy for the couple, recalling a vice-president of the World Bank who told me once: "Love is like money - you take it wherever you can find it." Except, being a banker, she said it the other way round.

And so the stage is set: the Aboriginal flag flies proudly over the House of Love, the barbies are firing up, the clothes are waiting to be put on and all I have to do is just stay off the champagne until I've performed my final duty, which is to make a speech - not more than five minutes long, I've been warned.

Then we have the wedding cake and the wedding song. No, I'm not allowed say what it is, but it's a mean number made famous by Dolly Parton and Kenny Rogers - and it's going to bring the marquee down.

Civil partnerships: How it stands in Ireland

• The Constitution does not recognise marriage between same-sex couples. Instead, civil partnership legislation - which is broadly similar to marriage - is likely to be introduced.

• Taoiseach Bertie Ahern has given a commitment to introduce legislation that will give same-sex couples legal recognition similar to that currently available to gay and lesbian couples in Northern Ireland.

• In April 2007, Kieran Rose, chair of Gay and Lesbian Equality Network (GLEN) was appointed by Brian Lenihan to the Board of the Equality Authority.

The first civil partnership ceremony in the UK took place in Belfast on December 19, 2005.

• The Colley Report, which investigated the question of civil partnership legislation for Ireland, is available on www.Glen.ie