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It was not until a fortnight after he was diagnosed as having leukaemia in March 1993 that Dom Hurford, then a sociable, music-loving 16-year-old, suddenly understood just how precarious his situation was.

"A group of friends had come to visit me and one of them asked me what it was like to have cancer. It was a huge shock. The word 'cancer' hadn't been mentioned. I didn't realise I had cancer. I remember crying and thinking: nobody lives after they have cancer. I thought it was a death sentence."

Thanks to pioneering treatment he received at Bristol Royal Hospital for Children, Hurford, now 35, recovered. And so inspired was he by the experience that when he left school he trained to become a doctor and found himself working on the wards where he had been treated. Almost two decades after his diagnosis, Hurford is championing a fundraising campaign to improve facilities at the hospital and make sure more young people can survive, recover and enjoy full, useful lives.

The onset of Hurford's illness was swift and shocking. "I was 16. My GCSEs were coming up. That week my band, Moody Cow, had played a couple of gigs and I was feeling a bit tired but I just thought I'd overdone it." Hurford, from Thornbury in south Gloucestershire, went out for dinner with his parents and fell asleep at the table. He woke up the next morning delirious, suffering severe abdominal pain and jaundiced.

Within days he was in Southmead hospital in Bristol and diagnosed as having leukaemia. He was the second person in the region to follow a new course of treatment – six months of chemotherapy with a dose once or twice a week rather than a less intense three-year course. "You're exhausted, shattered. I was sick every day for six months."

But without a bone marrow transplant, Hurford was given a four-in-10 chance of recovery. "Those didn't seem like good odds to me." He was moved to the Bristol Royal Hospital for Children, then sited in a Victorian building, and the search for a donor began. Nobody in his family was deemed suitable. Though it was relatively rare then, the doctors decided he would have to receive a transplant from an unrelated donor. "My donor is an amazing person who willingly donated her bone marrow without ever knowing me. I met her a number of years later. I was quite nervous – thank you just doesn't seem to be enough at all. We have met up a number of times since and she came to my wedding."

The transplant in September 1993 went well but the recovery was painful. "You lose the lining of your gut, you can't eat or drink anything. You have an ulcerated mouth and throat. You have this PCA [patient-controlled analgesia] morphine button. You need to use it to swallow, to do anything." But 24 days later he was told he could go home. "My bone marrow had kicked in, my counts were improving. I phoned my father at work and asked him: 'Are you busy?' Can you come and pick me up?'" It was a year before Hurford made it through a whole week at school, two years before he felt normal again. But he felt his life had "begun again".

Until his illness Hurford had no idea what he wanted to do after school, bar fantasies about being in a famous rock band. "But medicine suddenly seemed the natural thing to do. I had been surrounded by doctors and nurses. I'd got used to the environment. It sounds trite but it was my way of giving something back. I was on the receiving end of a fantastic NHS. Everything I needed – the chemotherapy, the bone marrow transplant – was delivered within a 15-minute drive from home. I decided, yes, I'll be a doctor, stay in the city and do what I can do."

He studied medicine at Bristol University, qualified in 2002 and has spent the last 10 years back in the hospitals and on the very wards where he had been treated. "Going back was an unusual experience," he says. At first he wondered whether he should tell children that he knew exactly what they were going through or "just do my job and be professional". But he remembered survivors talking to him. "It gave me such a boost knowing they'd got through it, they were having a normal life. So I'd chat and tell them: 'I know what it's like. I was in a bed here.'" He found that it also helped parents terrified that their children were not going to make it through. "It can be very emotional. It put me right back to where I was then. But then you see them improving and you know they are going to get through, and that is incredible. It was good for me to go back; it puts into perspective what I'm doing and why I'm here."

Hurford, now married with a two-year-old child, has been hugely impressed by the advances since he was a patient and is a fierce supporter of the children's hospital. "It was the first in Europe to be built around children. You feel that when you walk in." He is fronting a new drive by Wallace & Gromit's Grand Appeal, which since 1995 has raised more than £21m for the children's hospital. The idea now is to raise money to help move facilities such as the burns and neurosurgery units from Frenchay hospital in Bristol to the children's centre. The NHS is spending £30m on the core costs but the appeal is raising cash for pioneering equipment and additional facilities.

"Treatments have changed, everything keeps evolving. To push the boundaries, to improve things you have to expand, change," says Hurford. As a patient, as a doctor, he should know better than anyone.

• Wallace & Gromit's Grand Appeal is raising millions of pounds to support the expansion of Bristol Children's Hospital. To find out more visit: grandappeal.org.uk