Fredcat, as others have said, get your cat to the vet asp. Lack of food and fluid can make a slight illness, seem ten times worse as they're not getting the energy to fight for themselves, from the food they're eating.
If possible, boil a piece of chicken, and try to get some of the juice that you've cooked the chicken in, into your cat. If you have a syringe, (sometimes supplied with cough medicines) use that, but only 2 to 3 mil at a time. Or use a small teaspoon to get the fluid into her. Don't add anything to the chicken, whilst you're cooking it, no extra flavourings or anything. Just plain old water and chicken.
Any amount she has, will help her, and might encourage her appetite. But, get her to as soon as you can. As a previous poster said, you should be able to find your Vet on the net, and find out their opening hours for the weekend.
Will keep everything crossed for you both. xx