In the show Cercei was made out to be an alcoholic – in the books, does she drink an acceptable amount in keeping with the times ASOIAF is based on?

Well, I don’t know how much she drank in AGOT through ASOS, but starting with her AFFC chapters we can definitely see Cersei starting to fall into alcoholism – she drinks constantly and especially in relation to stressful events, she’s visibly gaining weight because of the extra calories (which takes some work with wine), etc.