Thirty-five may be a little young to be defeated by modernity, but I have always been more old-fashioned than my years. This morning I received an unsolicited telephone call from my GP's receptionist - a novelty in itself, though a welcome one. The doctor, she said, wanted to refer me to a hospital for some routine tests. I could choose from four hospitals, all in the area, but first I needed to come to the clinic and pick up a piece of paper with the necessary reference numbers and a "secret password".

It sounded mysterious and rather thrilling: a sort of health-care treasure hunt with a trail of clues leading to the blood test of one's desire. But I remember now - having spent most of the morning trying to decode my piece of paper, and the website to which it refers me - that I never was much good at brain-teasers. In fact, I haven't felt this tearful and frustrated since my grandfather tried to teach me the rules of the cryptic crossword.

The first difficulty is simply understanding what is required of you. It used to be the case, in the good old days of the patrician, high-handed GP, that patients were not expected to participate much in their own health care. If they asked for a referral they would be sent home to await a letter telling them where to go, and when. This suited me fine: I am confident that even the most doltish GP would have a better idea than I would where to go for, say, a decent tonsillectomy. And although I was aware of ominous talk in Westminster about "extending patient choice", I had no idea that the buzzwords had already been translated into reality.

So now it falls to me, with my E in O-level biology, to decide my medical destiny. Should I get my tests done at Bart's - London oldest hospital, I think, founded in the 12th century by a courtier of Henry I - because it has the romance of antiquity? Or would it be more sensible to go to the Homerton, which is round the corner from my house but has depressing carpets pockmarked with chewing gum? As a cat lover I am instinctively drawn to the Whittington - named after the real-life Dick - but the Royal Free is near Hampstead Heath, so I could combine it with a dip in the Ladies' Pond.

If I could make a more informed decision - based on the likelihood of my tests being done accurately, without my contracting a fatal superbug in the process - I would. But where does the ignorant laywoman find such information? My piece of paper suggests I try the NHS HealthSpace website, so, obediently, I do. I have heard about this website before, on Radio 4. It sounds like a great idea.

The aim is to provide a centralised national database containing all the directory information that doctors and patients might need, as well as secure access to the personal details of individual patients. Instead of craning to see what the doctor is scribbling in your medical notes (why is he taking so long? Is there something he hasn't told me?), you will be able to read it all online. There is also a "Choose and Book" service which allows you to browse appointment slots and pick one to suit you. It's the medical equivalent of online banking: convenient, practical, empowering. In theory.

In practice, it goes like this. In order to register, you fill in an online form and get sent an email containing an "activation code" consisting of numbers interrupted by hyphens. You then have to log back into the website and type in this code. Unfortunately, in the email the code is preceded by a mutant punctuation mark, which I haven't seen since there was a brief and inexplicable craze for it at school. It looks like this :- and I think it's supposed to be a more artistic version of a colon. One might be forgiven, however, for assuming it was merely a conventional colon followed by the first hyphen in the code.

It's a tiny thing, I know - and after four attempts I managed to crack the code, only to be apologetically informed that the Choose and Book service was not compatible with Apple Macs - but these are the kind of irritants that can render a brilliant idea unworkable. If the Government is determined to turn patients into consumers, with all the extra work and anxiety that entails, it should at least make it easy to navigate this strange new world of choice. Above all, that means giving clear, well-written guidance. It's no good spending millions on IT if the instructions are written by a grammatical anarchist who can bring down the system with a single punctuation mark.

Luddite though I may be, I am far more computer (and consumer)-literate than many of my parents' generation. It is the most fundamental principle of the NHS that it should be accessible to all, yet these well-meaning, sloppily executed reforms may create a two-tier system of access. The young, determined and scientifically minded will be able to find their way to the best care. The old-fashioned, impatient or technologically inept will give up in despair - myself included.

jemima.lewis@virgin.net