This is not a very happy life for your daughter, spending time with drunken adults and possibly heroin addicts, not the sort of environment any child should be in!
You sound like a resonsible parent and are obviously concerned for your child, and in all honesty I cant see this woman ever taking proper responsibility with this child or with her drinking habits, so maybe you should try and seek custody of your daughter, there are lots of single fathers and if you have the support from your family, they could help you...My 1st priority would be to go and see a solicitor, explain the sitch and see where it goes from there, it may be a long process, but it will be worth it in the end...a child needs stability and routine which im afraid she is not going to get from drunken adults, if it were my child, I would be seriously worried and would take action immediately!