I know this is a very old thread, but I just wanted to add to the above that Codeine in a very low dose (8mg in 500mg paracetamol) is freely available over the counter both as Cocodamol (general mid-strength painkiller) and branded as Migraleve (migraine-specific tablets), and shouldn't be confused with any Codeine-based medications prescribed by Drs, which will be higher doses and therefore more "risky" (hence why they are prescription only). As long as the guidelines are followed for the over the counter options (the main ones being don't take with other paracetamol-based meds, and only take for 3 days before stopping and consulting a GP) they present a low addiction risk, and are effective as a non-prescription analgesic (I would be lost without them - paracetamol and/or ibuprofen alone don't touch a genuine migraine).
I obviously don't intend to belittle your experience in any way Gordon, but I also wanted to give the "other side" (as it were) so that anyone with sensitivity to health issues/HA didn't read this thread and panic that they were at an immediate health risk if they had taken an over the counter codeine product