After you earn your GED, if you decide to begin your college career at a 2-year public community college, then it is unlikely that you will have to take SAT's … at least not now. Most community colleges do not require SAT's for admission. A public community college is often the best starting point for adult learners who have been out of the classroom for a while. It can be tempting to enroll in “online" colleges that promise convenient hours. But women in your situation commonly find that attending actual on-campus classes provides critical support from teachers and peers that online classes will not. You also need to be wary of the many less-than-reputable online colleges that take advantage of people in your situation by making promises of job-matching and career success that they will never be able to keep.
If you plan to start at a 2-year community college and later transfer to a 4-year college, it's possible that some of the 4-year schools you'll be considering will need SAT results (or ACT results, which are also accepted wherever the SAT is required). BUT … many 4-year colleges do NOT require test scores from transfers, especially those who have earned an Associate's degree (which is the degree you will earn at the community college after two years). Your community college course selection and grades will play the starring role in your admission verdicts (whether SAT's are required or not).
Because you have been out of school for a while, it might make sense for you to start at a community college and then, if you do need SAT's to attend a transfer college, you can take them later … after you have some math and English classes under your belt. (If you take SAT's after you've taken college classes, it should improve your test scores.)
It is also likely that, if you attend a community college, your college will have an “articulation agreement" with one or more 4-year institutions. Such agreements help community college students who have fulfilled certain requirements to transfer to participating 4-year colleges. Typically these requirements include maintaining a specified GPA and taking prescribed courses (often some English, math, science). So, if you start out at a community college, you should also arrange to meet with a “transfer counselor" at your college during your first semester to find out about articulation agreements and to get other information you will eventually need if you plan to continue at a 4-year school. You will also be able to ask the counselor if the 4-year colleges that take part in the articulation-agreement program will require SAT's. They may not.
On the other hand, if you decide that you want to go directly to a 4-year college right away, as soon as you earn your GED, without beginning at a 2-year school, then it is likely that you WILL have to take SAT's before you apply. SAT fee waivers are NOT currently available to GED recipients or to college students hoping to transfer. They are for current high school juniors and seniors only.
You can register for the SAT here: http://sat.collegeboard.org/registerWhen you are ready to choose a test date, you can look for the closest “test center" which will probably be a high school in your area. You will need a major credit card to register online or you can register by mail using a check or money order. Alternatively, you can consider applying to one of the hundreds of college that are “Test Optional." You will see a state-by-state list of these colleges here: http://www.fairtest.org/university/optional/state
Admission officers will have a lot of respect for you because of this effort you are making to continue your education and to provide a brighter future for your children. Many are likely to do what they can to support your efforts. So as you begin the college selection and admissions process, be persistent and don't be afraid to ask for help when you need it.
All the best of luck to you.