Success

 After retopologising the head, I found that the rest of character was really easy to understand the flow of the polys that I needed. Also the baking of the normals has been something that has always seemed daunting to me as I've never really understood the process. However, once I got started with it and saw the results, it felt a lot easier to bake each part.

This seems like a much stronger bake than I had for the head, and has picked up every detail of the character very well.

The difference between the two models visually is very minuscule, which I feel makes the retopology a success, however I feel like I made the bones on the character's arm sockets a little too low poly, however not by too much to be noticable.

As seen on the wireframe, the difference in polys is huge, the original character on the left sits at 287k tris, while the retopologised and baked character on the right sits at 8.5k tris. I do feel as though I could have gone quite a bit higher with the polys on the retopped version to allow for a few smaller details to really be visible.