You'll be able to pick it up from your local chain chemist. It's behind the counter, tell them you have migraine or severe back pain. You'll have to go to another one close by if you want more than one packet. I just outright ask fro it, I've never been questioned.
I use Paramol for CWE's.
When me and MTGG used to buy Codeine Linctus everyday in Manchester, we'd alternate between 5 different chemists in local area, both of us taking it in turns on different days. Only the smaller non chain ones would sell it to me. Though, I did succeed in getting it from Lloyds once, by spouting some shite that I'd learnt to trip off my tongue. Though what I've just written is not at all relevant to CWE's.