To get your fonts go to Dafont.com
To get them onto gimp
Once downloaded, open gimp go to File>Prefrences then click where you would click to open up the brush department and go to Fonts and click on the paper thats folded then upload your font from your fonts folder and click ok and it will be in fonts.
Same thing as brushes except you click fonts and go to the fonts folder instead.
NOTE: You also dont have to log out of gimp once they are loaded.