Can’t find any letters? Don’t own a smartphone? You’ve got options. You can call NHS 111. Yes, the same number you use for minor emergencies and that one time you ate a bad kebab.
Tell them, “I don’t know my NHS number, and I need help finding it.” They will not laugh at you. They deal with weirder stuff, like people asking if they can swap their appointment for a free toaster.
Pro tip: Have your National Insurance number ready. That’s the nine-digit one the tax office loves. The NHS system can cross-reference it. It’s like a spy trade-off, but with less trench coats.