Hi Alan,
Gorillas are great to photograph.. Good pic.
Instead of using or buying photoshop or Lightroom, Shoot in RAW on your camera. Then it comes with Digital Photo Professional. Its fantastic software and its free. The good thing about shooting RAW is that you can play around with exposures , white balance, even Black and white.. Then convert to JPG when your done. Very easy to use, and if your unsure how it works, go to the Canon Learning Center ( google it, sorry don't have link handy) and they have some excellent tutorials on how to get the most from the software. I find it much faster for what i do , but everyone is different.
Good luck
thegary