If referring to butt itch.... I have a very cost-effective way to help with this! Tucks pads are great but they are basically pads with witch hazel and VERY expensive (also quite small in my opinion). I buy regular bathroom/flushable wipes (all the toilet paper brands make one but you can also get 'generic' versions at drug stores like CVS and Rite Aid for even cheaper) and then buy a giant bottle of witch hazel (generic again at CVS or Rite Aid) and dump a bunch in the wipes tub so they are soaked really well. MUCH cheaper than the Tucks wipes and the toilet wipes are bigger. Also then BLOTTING dry afterwards helps (as opposed to wiping which can be irritating) but important to dry to prevent chapping. Just a suggestion that has worked well for my husband. Plenty of good creams out there as some have suggested too, esp. diaper rash creams (like Desitin). I have done this stuff myself during UC flares as I also have hemorroids and can get very irritated and itchy.

As far as the codeine, there may be other narcotics that don't make you itchy. I can't handle some but am fine with others. If it works for you I would hate for you to have to give it up. So speak with your doctor about other options. I believe you have less options/variety in the UK than in the US (we have codeine, hydrocodone, oxycodone, etc.) but I don't think you have as many. Like I said, people can have an issue with one but be fine with another. Paregoric (tincture of opium) helps some people and isn't as addictive/debilitating as some may think (you don't get totally high from it!) It's just enought to slow things down. Also, it hasn't been that long since your colectomy so often things do improve with time. Hopefuly they will for you.

Good luck to you!