Blink and you could easily miss The Meriton, on the St Philip's Marsh industrial estate.

The modest single-storey school building seems out of place amid the surrounding commercial buildings and lines of parked cars.

Go through the front door, and you are greeted by another unexpected sight: baby carriers.

There are so many of them that they are stacked on top of each other in a haphazard pile in the hallway.

For the pupils who attend The Meriton in Bristol do not arrive with schoolbags slung over their shoulders like most teenagers.

Many come holding babies in carrier seats. Others are about to give birth within months or even days. All have had to leave mainstream schooling after becoming pregnant.

Anyone driving along the muddy roads of the industrial estate and seeing teenage girls coming through the doors of The Meriton holding baby carriers might assume that it is little more than a dumping ground for Bristol's real-life Vicky Pollards.

But walk beyond the pile of baby carriers and into the classrooms and the nursery, and it becomes apparent that this is a place giving Bristol's young mums opportunities to build a future for themselves and their children.

The high standard of education and support provided to pupils at The Meriton Young Parents' Education and Support Unit was recently acknowledged in an Ofsted report that described it as 'outstandingly good'.

"It's our hat-trick," declares head teacher Carol Bowery. "This is the third Ofsted inspection in a row that has described The Meriton as 'outstandingly good'.

"The aim here is to find ways in which our young women can find their strengths, as sometimes school has been a bit of a challenge for them.

"It's important to do that because if a young woman is having her own needs met, then she's better able to meet her child's needs."

As we speak in the school office, pupils are wandering in and out to use the water machine or to talk to staff.

"We have an open-door policy here," says Carol. "Besides, I really enjoy being around these girls. They're good fun, and they teach you a lot along the way. They keep you grounded."

We make our way to see the five classrooms and the nursery, passing bookshelves in the corridor containing videos with titles including Romeo and Juliet, Grease and Managing Anger and Strong Feelings.

"We look at relationships as part of the work we do here," says Carol. "There's a broad curriculum here which includes academic qualifications, vocational training and personal development."

It is serenely calm in the nursery. Some older babies are playing in a corner, while some very small babies are being looked after by nursery nurses and a young mother has just changed her baby's nappy.

Things are less peaceful in the kitchen and dining area, where a tiny, delicately pretty girl is complaining that she wants a takeaway for lunch as she doesn't like what is on the menu.

Her truculent manner reminds me of the way in which my children behave when they want their own way. It seems strange to think that although this dainty girl is little more than a child, she also has a child of her own.

Yet no matter how young they look – or, indeed, actually are – the schoolgirl mothers at The Meriton are never treated like children by Carol and her staff.

"It's important that they have opportunities to have an adult conversation," says Carol.

"We want to give them a good education and also build their self-confidence and their self-esteem so they can take a full part in society.

"We do that by treating them with respect and giving them new opportunities, whether it's doing art, drama, car mechanics, floristry, or going on to do a degree.

"They want to do well, and they want to achieve. And they do achieve. We've had girls go on to do university degrees, while others have become learning mentors, nursery nurses, florists ... whatever they want to be."

Among the options available at The Meriton are: basic literacy and numeracy; GCSEs in various subjects, including English and Maths; BTEC health and social care; floristry; car mechanics, and textiles.

"We have a timetable and lessons, but we also collapse the timetable sometimes to do whole school activities," says Carol.

"We have to be flexible anyway. We've had waters breaking here, and if a young woman is breast feeding someone from the nursery will come and get them from their lessons if they are needed."

There are now more than 20 staff at The Meriton, including a midwife and a sexual health visitor.

"There used to be only three staff in two very small huts," says Carol, herself a mother of two, who has been working at The Meriton for 23 years.

She shows me some old photos of mothers and babies at The Meriton, with all the pride of someone going through a family album.

"It is a bit like a family here," she observes. "And like every family we have our moments."

About 30 young women are transported to The Meriton each week from within Bristol and also from neighbouring education authorities. Some are already mothers, and others are pregnant.

Zara Ball, 18, who was previously a pupil at St Mary Redcliffe, and Briony Timbrell, 17, who was previously at Fairfield School, are former pupils who have returned to The Meriton to study.

"I came about three years ago when I was a couple of months pregnant with my daughter Scarlett, who is now two-and-a-half," says Zara, who lives in Fishponds. "I came here and did my GCSEs and then went to college for two years and did a National Diploma in Art and Design, which I also passed.

"I've come back here for a year because I'm two months pregnant with a second child. I'm doing a Health and Social Care BTEC, and then I'm going to the University of West of England in September to study Adult Nursing."

Briony Timbrell, whose daughter Hermione is 19 months, is also pregnant again, and is taking a Health and Social Care BTEC with the aim of studying midwifery at university.

"I came here in Year 11 when I was about four months pregnant," she says. "If I hadn't come here I doubt I'd have passed my GCSEs. I was rarely at school before I got pregnant."

Zara, who is now engaged to Scarlett's father and will be getting married next year, adds: "To be honest most of us found it difficult at school, but they're very good at keeping you focused here.

"Having a baby rescued me. It's made me more determined to get an education, so I can set up a life for her."