Hi and welcome
I'm not sure how long withdrawal will take or how difficult it will be for you.I can tell you that it will be worth it.We have some good forums here.You might want to check out the NA board.There are lot of supportive people here,and perhaps someone will have experience with codiene.Is that what you've always used,or have you had problems with other substances?
In any case,keep posting.We are glad you are here.
phoenix