If, as the Gothy makeover and dramatic artwork for her new album suggest, Sarah Brightman is heading to the dark side, she is going to be jolly polite getting there. Today she is all in black, with smudgy eye make-up and tousled hair (including two absurd plaits coiled around her head); yet any hint at rock-chickiness is undone by her cherubic prettiness, girlish voice and turbo-professionalism.

As a solo artist, Brightman has sold 26 million albums and two million DVDs in 34 countries. Her musical styles fuse opera, pop and jazz. She is huge in the States but not here – the image of her and her second husband, Andrew Lloyd Webber (he much older, she his muse) seems for ever frozen. Symphony, Brightman’s new album, includes collaborations with Andrea Bocelli and Paul Stanley from Kiss (“Some of the themes are quite dark; they required a rock sensibility”).

The 47-year-old singer talks about the album coming out of a “very dark time”, including her decision to give up trying to have children – this after an ectopic pregnancy, two miscarriages and IVF. “People have suggested I could adopt,” Brightman says. “But work is central to my life now. And so I am going to put it to one side. After a while not having children becomes the norm and perhaps that might sound alarming, to parents especially, but I have never known anything different. I’m not traumatised by not having children. My life and career are incredibly rich.”

If she seems content, perhaps this in part is also down to a new boyfriend, the 41-year-old Bulgarian-born Louis Oberlander, a music studio technician she has been seeing for a year. “I knew him for about six months before he asked me to go to the cinema. I was completely shocked when I found out he liked me.”

She isn’t sure if she’ll marry him, though “love is incredibly important. I don’t just mean in the boyfriend sense but generally. Nothing works, or is worth anything, without it. It’s the centre of everything – why you have ideas, do things”. Brightman relaxes by cooking and enjoying art and architecture, but she is a fearsome grafter, and perhaps one of the reasons that she is not loved here is that British mistrust of drive and ambition. That, and her octave-swooping voice, which you feel should come with its own dry-ice machine.

She says things that sound self-aggrandising on the page, but are said without hauteur. So, talking about growing up in a large family in Berkhamsted (father a property developer who later committed suicide), she says: “I was gifted as a child, and very musical. I seemed to be good at anything to do with the arts. At 5 I understood the music I was dancing to and had an eye for costume.” She first appeared in a West End musical at 11 and loathed boarding school. Stage school (“I had such freedom there”) followed.

Brightman led the saucy dance troupe Hot Gossip and had her first hit with I Lost My Heart to a Starship Trooper in 1978. At 18 she married a music manager called Andrew Graham Stewart. “I was probably in love but I can’t remember. Girls change such a lot between 18 and 22. It didn’t really work out.” In 1981 she was spotted by Lloyd Webber. She became his leading lady in Song and Dance, Requiem and Phantom of the Opera. They married in 1984.

Brightman says she felt hostility “from the beginning. I haven’t tried to understand it. I’ve done very well everywhere else, especially the US, where I now live, I just accept it for what it is. The more you are away from Britain, the more you appreciate it. But I don’t miss it, although I miss my family. Our profession can be uncomfortable but I enjoy what I do. I get on with it.”

She smiles a huge, oddly alarming smile. “The only person who scares me sometimes is myself.” What does she mean? “I’m courageous but sometimes to go forward is scary, whether it’s touring in a new country or working with new people. But I’m very instinctive. I can’t explain why I do things. I just do them.”

When her father committed suicide she performed that night in Aspects of Love. “Some people might find that shocking or callous,” she says, “but I was in shock, it was my way of coping.” She is still friends with Lloyd Webber (they divorced in 1990), and her partner before Oberlander was Frank Peterson, who is still her producer.

In the cover art for Symphony Brightman appears, in a series of dramatic sheath gowns, freaked, haunted and hunted in a Dungeons and Dragons-style cartoon landscape. It matches her otherworldly spirit. “It’s what’s been going on in my soul and head,” she says. “It’s about somebody running away from something – it could be evil. She’s running towards a forest of light, then she dies and her spirit rises to a nowhere land, where she goes through a door to a tree cathedral. But then she ends up coming back to the beginning again.”

Hmm, right. Brightman says these outlandish visions derive “from a lifetime of working incredibly hard and then suddenly, at a certain age as a woman, you think, ‘Hang on, what have I been doing? What’s this been about?’ Making the same mistakes . . . It was like a strange nightmare.” She’s never had therapy, she says; she knows “good and evil” run parallel in her life. Approaching 50 doesn’t bother her.

Brightman talks easily about Lloyd Webber and his TV success – she doesn’t agree that the Joseph and Nancyshows are exploitative or free advertising for him. “You can’t put down millions of people’s enjoyment by saying they’re wrong.” She doesn’t know if she could judge on such a show. Would she do another musical? “Well, I never say never but eight shows a week is hard.”

An international tour is next. Does she ever feel like kicking back a bit? “I do what makes me happy. And I love to work.” In August she will appear in a rock-opera movie, Repo! The Genetic Opera. (Her co-star, Paris Hilton, was “charming” and reported to work on time and “without dogs”.) As she picks up her coat, Brightman cheerily says she is off for fish and chips. Part of her obviously dwells in the everyday, as well as getting lost in forests.

Symphony is out on Charisma/Manhattan EMI

Explore Music

• Proms

• Festivals

• CD Reviews

• Live Reviews

Editor's choice

• The top 10 fan versus band scuffles
• Mamma Mia! The first review
• Times critics' 20 best films for kids