First, we need to understand the halacha for men, and then we can apply it to the case of women. Although prior to Kiddush one can usually not eat or drink anything, a man, upon awaking on Shabbat morning, may drink the same light drinks that are permitted before davening on any other day.‎{&&1}‎ This includes water, tea, or coffee without sugar. Many have the custom to add sugar‎{&&2}‎ or milk to the tea or coffee, which is easier to justify if that is the only way they consume those drinks.‎{&&3}‎ The reason that it is permitted to drink these beverages before Kiddush is that there is no obligation to make Kiddush before davening. Since Kiddush must be accompanied by a meal of some sort and it is forbidden to eat before Shacharit, the obligation to recite Kiddush begins only once Shacharit has been completed.
If a woman always davens Shacharit before eating (and does not rely on a short prayer to HaShem after netilat yadayim, as was once customary), then her situation is identical to that of a man regarding Kiddush. However, if she does not daven Shacharit regularly, or if she regularly eats before davening, then her obligation to make Kiddush applies immediately, and she should not drink before making it.‎{&&4}‎
If a woman feels somewhat weak when she gets up or as the morning wears on (not to mention if she is actually sick) and she cannot make Kiddush at that time, then she can drink and even eat as needed before Kiddush.‎{&&5}‎ The rationale for this leniency includes the fact that there is an opinion that women are not obligated to participate in Kiddush on Shabbat morning. If she has already davened, there is no halachic reason why she cannot make her own Kiddush and solve the problem. However, if, like some women, she feels uncomfortable doing so before her husband comes home, and not drinking anything is hindering her oneg Shabbat, she can also rely on the lenient opinion and eat prior to Kiddush.