Hiya Denise, Welcome to the friendliest cat site I have found after The Hovel, I would book a vets appt, take them all down and make sure that they are all wormed, vaccinated etc before they find new homes, but will also make sure that Mums aren't anaemic ect. PDSA are very good in these situations as are Blue Cross, if there are any relatively locally, it might be worth the petrol money to visit? I don't know and wouldn't want to know what your income bracket is, but RSPCA, as well as the other organisations mentions do free spaying for people on low incomes.
Hope that helps.