In TortoiseSVN, patch applying does work. You need to apply the patch to the same directory as it was created from. It is always important to keep this in mind. So here's how you do it in TortoiseSVN:
Right click on the folder you want to apply the patch to. It will present a dialog asking for the location of the patch file. Select the file and this should open up a little file list window that lists the changed files, and clicking each item should open a diff window that shows what the patch is about to do to that file.
Good luck.