Of all the thoughts that flashed through my mind as I fell from 15ft up a ladder one morning last May, the potential financial cost of my unexpected descent was not one. I had been trying to paint the weatherboard above the bedroom windows of our house; a whim that had occurred to me in the middle of the night (as these things do) while working out chores for my week's holiday. Unfortunately, I reached just a little too far on a ladder just a little too short, and suddenly felt it slide from under me. Bouncing off the wall, knocking off the guttering and a carriage lamp in the process, I eventually collapsed in an inelegant heap on top of the ladder.

In the agonising hour that followed before our next-door neighbour arrived home and found me whimpering piteously for help, left leg utterly unresponsive, I had time to think of many things – including how stupid I'd been – but never the implications of my future treatment. This was Britain, after all. I would, without question, query or censure, be treated by the NHS at no cost to myself.

Not so, perhaps, had I bounced off the front of my parents-in-law's house in Houston, Texas. They are in their early 80s, expatriates from Britain for more than 50 years, and have followed my medical care with what I now realise is more than solicitous interest, thanks to the vitriolic US healthcare debate of recent weeks and the slagging-off that British medicine has received as a result (why do Americans always home in on the state of our teeth?).

When we spoke last weekend, my mother-in-law, Sheila Thurau, had just received a letter telling her there was only $945 (£570) left to spend on treatment for her this year, under the US government's Medicare scheme for over 65s. As her current bill for the sort of medication 82-year-olds need – blood pressure tablets and the like – comes, so the letter informed her, to $262 a month, it will be a close-run thing whether she emerges in credit.

Essentially, the state funds the first $2,700 each of the annual cost of their medications and treatment. Beyond that, they pay the rest up to a limit of $4,020, after which they qualify for what is called catastrophic coverage, where the state picks up the extra costs.

Of course, if they were younger they would have to be paying medical insurance – the average annual cost of a family policy tops $12,000. Without it, as they discovered from their doctor in Houston, an accident like mine might leave you facing life-changing bills upwards of $75,000.

Back here, once my neighbour had raised the alarm, not one but two ambulance crews arrived within minutes. I thought I'd only dislocated my knee but they knew better. I'd shattered my tibia, a plateau fracture that left fragments of bone floating about aimlessly in my leg. They haven't shown me the x-rays yet, but my wife says they're quite spectacular (one of my doctors said it was the best break they'd seen at the hospital for at least three weeks). The ambulance crews turned up at my bedside at the end of their shifts out of professional interest. Ah, they said sympathetically, they'd known it was a break, but hadn't liked to tell me.

Since then, at our nearest accident and emergency hospital, the Kent and Sussex in Tunbridge Wells, I've had the services of consultant orthopaedic surgeons, anaesthetists, doctors, nurses, ambulance crews, physiotherapists, x-ray staff, porters and even chaplains. Until last week, for 14 weeks, my leg was encased in a complicated and sophisticated exterior framework with metal pins and wires binding the bones back together. Now it is just bandaged from knee to ankle and bound in splints. I hop about on hospital crutches and a zimmer frame and an ambulance calls when I need a hospital appointment.

I have so far spent three weeks in hospital, had four operations under general anaesthetic, daily home visits from district nurses and face weeks, if not months, of more care. Yet I have never been asked for my credit card or insurance documents before treatment, as I was the only time I fell ill while visiting the in-laws in the US. No one has murmured that this treatment or that service might be a little on the expensive side, or will incur a delay. And no one – despite what conservative Republicans allege – has yet questioned whether my life is still worth living, or whether amputation would be cheaper.

I can't tell what my treatment has cost the NHS, but I have some idea what it might have been in the US thanks to the in-laws' doctor, who gave an estimate based on prices in Houston. The figures are eye-watering. She reckons: $12,000 per operation; up to $3,500 for anaesthetics each time; hospital at $500 a day and ambulance $300 a trip. That's not counting the cost of medicine. It adds up to more than $76,000, or at least £47,000. We'd have had to sell the house I was so rashly attempting to paint.

I am, understandably, profoundly grateful to the NHS. As it happens, during my 55 years I have had more than my money's worth out of it. I have been an insulin-dependent diabetic for 22 years, and in recent times have needed treatment for a range of other sundry ailments: frozen shoulders, kidney stones and retinopathy in the eye. My pre-existing medical conditions would give American healthcare schemes a coronary.

Of course, in the US I'd probably have had medical insurance (though more than 40 million Americans don't) but mine would almost certainly have cost more than the $12,000 national average. Perhaps I'd have been in a company health scheme, but employers are cutting back on those too, limiting cover and restricting availability to new staff (hence affecting employees' ability to change jobs).

In Britain, only once have I gone private, after I was told there was a nine-month wait to use the new, multimillion-pound NHS-provided MRI scanner at the hospital to investigate my aching shoulder. Such was the pain and inconvenience, I invoked my membership of the Guardian's company scheme and was booked in for an appointment – same scanner, same specialist, same hospital, same treatment – within the week. I felt rather ashamed.

To be fair, the Kent and Sussex would not be everyone's first choice of hospital. Built in the 1920s in art-deco style and opened by the young Queen Mum while she was still Duchess of York, its dated charms are fading. Round the back it degenerates into a clutter of modern buildings and converted huts. Much worse, it is part of the NHS trust where more than 90 patients died in C difficile outbreaks between 2004 and 2006, after revelations that conditions in parts of the trust's hospitals were scandalously filthy.

But that's not true any more. My treatment has been exemplary and the shortcomings have been administrative, as far as I can tell, rather than medical. I could have done with more information from the doctors about my condition, but I guess a slightly patronising manner comes with the job and, if you must fall unnecessarily off a ladder, perhaps dimness is taken for granted.

The orthopaedic wards are still crowded and mixed, unlike in the US; few beds are left empty for more than a couple of hours, even in the middle of the night. "It's very seasonal in here," a nurse told me. "In winter we get little old ladies who have fallen over on the ice. And this time of year, it's middle-aged blokes like you who've fallen off ladders."

Sometimes my ward was full of men and sometimes elderly women, not always segregated even on opposite sides of the ward. A senile, elderly man would constantly call out "Help, help, help" night and day, interspersed with even more desperate cries of "Wee, wee, wee", and kept uncovering himself as he tried to get out of his bed a few feet from an equally elderly female patient.

"Cover yourself, Henry," the staff would cry cheerily as they passed. "You'll excite the old ladies and just make the men jealous!" His wife sat desolately by his bed most afternoons, telling him not to be a naughty boy. The not unexpected news that a recovery was unlikely was broken to her in front of the rest of us by a junior doctor. "We've been married 55 years," the old lady said sadly. The scene made voyeurs of us all.

Every ward I was on seemed to have a Henry, shouting through the night. That would have been different in the US, where the norm is for single or, at worst, double-bedded rooms. A nurse said to me: "We wanted to put Henry in an isolation room, but unfortunately we needed it for swine flu."

More alarming was the hospital's reliance – I am sure it is not alone here – on agency nursing staff to cover shift shortages, some of them clearly deficient in English and in training. I watched one evening as the ward sister attempted to explain to one that she wanted him to fetch something. He stood at the end of my bed, murmuring "fetch? fetch?" – clearly not having the faintest idea what he was being asked to do. The sister went and did the job herself.

On another occasion, I handed an agency nurse my full urine bottle – few things are hidden in hospital – and she looked around, wondering what to do with it, before spotting the basin where staff wash their hands and pouring the contents down the plughole. When I told a staff nurse what she'd done, he turned white and rushed away to get some bleach.

"I wouldn't mind if the agency staff had any qualifications, but we have to take them on trust," a ward sister told me. "We just don't know when the agency cover turns up what they can do. I find it's best to treat them as if they know nothing and then I won't be disappointed."

Later that night, I spotted the same sister telling the agency nurse that she couldn't sign her timesheet because it said she had done two hours more than she had. A ward orderly said: "It wouldn't be so bad but, because they're agency, they are paid twice as much as we are. It does cause resentment, especially when we have to do their jobs as well as our own."

The hospital's wards were staffed, even in deepest, bluest Kent, with a united nations of regular nursing staff. Filipinos, Indians, Africans, Portuguese, Brazilians, Italians, New Zealanders, eastern Europeans: the NHS would collapse without them. The Polish and Czech nurses brought an air of exoticism with them and a wistfulness too, as they crowded round the ward television set – the only time it was on – to watch the Eurovision song contest. They were, almost without exception, brilliant and dedicated. As I apologised to one young Polish nurse for some imposition, she replied, smiling: "I don't mind. You remind me of my Dad," which may not have been entirely good for my self-esteem, but did lift my morale. Another, inspecting the web of wires connecting the metal frame to my leg, said wonderingly: "I think that's really cool. When you see those, you know it's a really good break."

If this seems like the familiar picture of the NHS groaning under the strain, then there's something else too. On the outskirts of town, on the site of the old Victorian Tonbridge workhouse that has for many years been a maternity hospital, a new £225m PFI hospital – one of those controversial private finance initiatives where private money funds public provision – is finally arising to replace the Kent and Sussex. A forest of cranes crowds across the landscape, the site is lit up at night and, a year after work started, the framework is in place. In two years' time it will be open, with every one of its 500 patients in individual rooms, not wards, just like in the US. It will be state-of-the-art. I should have waited two more years to fall off my ladder.

Back in Houston, my parents-in-law are ruminating on the cost of their healthcare, at the complexities even of the state-provided Medicare system. The talk among the oldsters on their estate is how much you have to pay for drugs or operations, and whether it is cheaper to buy medication in Canada. Some of their friends are struggling to find $185 a month to pay for a drug that delays the onset of Alzheimer's.

My in-laws' fear – and ours – is what, God forbid, will happen if they need surgery, or even a short-term hospital stay. They fear the cost of unexpected illness. Sheila recently had to haggle with local dentists over the cost of capping one tooth: her usual dentist wanted $500 but she found another, rougher, practitioner who charged $300. Her basic hearing aid cost her nearly $1,400 – a deluxe model would have been twice as much.

Much as my own grandparents in England feared ending up in the workhouse, my in-laws fear falling into the state-provided Medicaid system (one step down from Medicare), for which you need to be destitute to qualify. Father-in-law Vern says 60% of US bankruptcies are triggered by medical costs.

"No one who has been through illness in this country worries about socialised medicine," he says. "We know there is a lot of money and vested interests in play, lots of fire and smoke.

"They are so ignorant about the NHS. It doesn't help when this idiot from the Conservative party comes over and talks down the service and gets lots of publicity. What sort of kick is he on?"

I don't like to tell him that Daniel Hannan is one of our local MEPs. "To our knowledge, he's never visited one of our hospitals," says a trust spokesman. But then, of course, health is beyond his remit.

Some names have been changed.