I know that Alateen is in the UK, so you might want to check with the local AA office or just call the number for AA in your phone book.
If there is an Alateen meeting or two a week in your area, it might be an idea to allow SD to go. There she would find 'peers' that will fully understand what is going on with her and will have either been where she is or be where she is now.
Alateen has helped many many teenagers with alcoholic family members.
It sounds, however, like you and hubby are giving SD a GREAT STABLE home and lots of love which is so important at this age!
Love and hugs,