I would recommend getting your actual high school diploma instead of getting a GED. While the two used to be seen as equal, more and more colleges and employers are seeing a high school diploma as more valuable. The reason being is that to earn an actual diploma, you have to complete all of the required work, where as with a GED, you simply have to take a test. Studies have shown that high school graduates are more likely to pursue higher education, and more likely to finish their degrees than GED holders. Also, when it comes to salary, a high school graduate makes about $10,000 more per year than either a high school dropout or a GED holder.
If you are looking for a place to go back to school and earn your high school diploma, there are several online schools. Just make sure that they are accredited, and the accrediting agency is approved by the US Board of Education. I would recommend The American Academy. Here is their website-
http://www.theamericanacademy.com
I hope this helps! Best of luck, and congrats on your decision to go back to school!