This is shockingly common. Your number might be buried in an old prescription box or stashed in a forgotten email. Check your NHS app if you’ve used it before—it’s right there in your profile. No app? Call 119 (the non-emergency helpline) and ask nicely.
If you’ve moved between different countries in the UK—England, Scotland, Wales, Northern Ireland—your number might still work. They’re all part of the same system, but local quirks exist. Just tell your new GP your old info and let them sort it out.
Oh, and if you’re an EU citizen with a European Health Insurance Card (EHIC)? That doesn’t give you an NHS number—it’s a temporary pass. You’ll still need to register for full, long-term access. Sorry, no shortcuts here.