Done it! I pretended I was talking in AA, since that is the time I am honest with people. Just said it like it is. She had a bit of a fit about the amount of ibuprofen I was taking but was quite calm about the codeine.
Referred for physio. Now it's on my NHS records and will be with me for life. But curiously, I do feel better for having done it. Let's hope I never need real pain relief!