The 35-year-old Briton starts his challenge on 26th August accompanied by two other ex-servicemen and a mountain guide, aiming to fundraise for two charities and prove to others with life-altering injuries exactly what's possible.
For Heritage, from Poole on England's south coast, it's the latest in a string of physical challenges that, 12 years ago, seemed far out of reach.
In 2004 Heritage was on his second tour of Iraq as an electronics specialist for a bomb disposal team when he was gravely injured.
“We were clearing devices on a route one morning and I got blown up by a suicide bomber in a car; he drove up near me and blew himself up,” Heritage tells The Local.
Aged just 24, he had to have both his legs amputated above the knee. He was the first soldier to suffer such a serious injury and survive, and doctors at the time thought he would never walk again.
“There were very few people in the UK with that injury. So the norm was that you wouldn't walk,” he says.
“It's more common now because there are a lot more soldiers, younger people, who are fit enough and healthy enough to do it.”
But Heritage wasn't simply going to accept the prognosis.
“My goal was to be independent, free from a wheelchair, able to walk around,” he says. “I was told that was unrealistic but that was where my head was.”
“I think you've got to give it your best go. And then if it doesn't work out at least you've tried.”
It took him five years of hard work to finally be able to walk freely on prosthetics and regain his independence.
Keeping fit to keep going
Key to his success was fitness, as using prosthetics is physically draining.
“It's part of my day now; I get up, I put my legs on. But it's still noticeably hard,” he says.
“It takes a lot more energy for me to walk around on my prosthetics than it does generally so you have to be quite fit to get mobile.”
As a result, while before his injury Heritage didn't have a lot of time to dedicate to fitness, now it's central to his life and has sparked a passion for physical challenges.
Over the past few years he has learnt to ski, taken up scuba diving and rowed across the Atlantic as part of the inaugural crew of Row2Recovery, which raises money for military charities.
“I think mentally that was the thing that pushed on my rehabilitation and made me realize I can do stuff,” he says. “It was also the worst thing I've ever done in some respects. It was six of us, you'd do two hours rowing, two hours off, round the clock for a couple of months. I've not been recommending that to people!”
Maybe not, but having the goal of a significant challenge like this is what's kept him motivated.
“I've got to keep fit so for me it's nice to have something at the end of it, rather than just endlessly going to the gym. It's training me to do something. That's what keeps me going I think.”
Neil Heritage on a training climb. Photo: Neil Heritage/Endeavour Fund
He had the idea to climb the 4,478m Matterhorn two years ago, partly because “it hadn't been done by anyone with my disability”.
A below-knee amputee – Scotsman Jamie Andrew – managed to summit Switzerland's iconic mountain earlier this month, but as an above-knee amputee Heritage has had different challenges to overcome.
“Having an artificial knee joint doesn't help me so I don't have a knee joint on my climbing legs,” he says. Instead he has “a kind of rigid pole at the bottom of my leg” and a disk-shaped foot which acts as a crampon.
He spent time in Switzerland last year trialling his climbing prosthetics and assessing his ability with the guide who will accompany him.
“He is an experienced Matterhorn guide so he knows a lot about the mountain but not about people with disabilities. It was quite difficult to find a guide who was prepared to have a conversation about taking me up! That was part of the battle early on.”
He, his climbing partners Steve Green and Mark Hooks and their guide are aiming to complete the whole climb in three to four days, longer than usual, by staying at least one night at an emergency shelter on the Matterhorn rather than trying to reach the summit and back in one day.
The climb is supported by the Endeavour Fund, created by Britain's Prince Harry and the Duke and Duchess of Cambridge to offer seed funding for sporting challenges undertaken by injured servicemen and women.
And the trip is fundraising for two charities close to Heritage's heart – Row2Recovery, and Scotty's Little Soldiers, which helps the children of soldiers killed in action.
"We are all fathers and we all lost friends who had children so that's why we picked that charity. "
But tackling the Matterhorn is also about showing people with similar life-altering injuries that anything's possible.
“I think the general consensus is it's moving things forward and it makes it more possible for everyone else,” says Heritage. “It's all positive stuff.”