A long back story lives in GP notes, referral letters and scan reports. When you need the file, for a move, a second opinion or your own records, the UK gives you a formal way to ask for it.
How do you get your medical records in the UK?
By making a subject access request to whoever holds them, usually the GP practice or the hospital trust. It is free, it must be answered within a set period, and the NHS explains the route on its page about how to get your medical records.
For most purposes the summary is enough: problem list, medications, referrals. The full file exists if you need it.
What do other countries publish about their public documents?
More than you might expect, and the structure is instructive. In the US state of Georgia, for example, the Georgia public records desk maps which office holds which document: open-records requests with a three-business-day response, the twenty-five-cent copy rate, and where court filings and certificates actually live.
Different country, same lesson: the document you want has a named holder, and finding the holder is most of the work.
What is worth asking for before a new practitioner?
The referral letters and imaging reports, not the whole file. A new osteopath or physiotherapist works better with the last scan report and the list of what has been tried than with a hundred pages of appointments.
Our page on choosing between an osteopath and a physiotherapist covers the other half of that first appointment.
Are there limits on what you can see?
A few: information about other people, and material a clinician judges likely to cause serious harm, can be withheld. In practice the obstacles are usually delays and forms, not refusals.
For how treatment itself is arranged on the NHS, see osteopathy on the NHS.