Cats don't show they are sick, for the most part, until they are very, very sick. I don't think there is a member of this board who would wait until the weekend to take in a cat with these symptoms. If it is diabetes, she could crash suddenly. If it's renal failure, the sooner she is put on treatment, the greater the likelihood that you will have years more with her. I believe she is eating salty things because the large intake of water, and peeing it out, has thrown out her electrolytes and she is trying to balance the losses.

You say she had some kind of vaccincation when young. Has she not had to see a vet since then?