Finished getting the normal map sorted. Doesn't look too bad though I think I may add some extra geometry for the bumps around the base because they're a bit too big to get away with faking. The rest I'm quite happy with so here is a comparison.
low poly Model
High Polygon sculpt
Normals on the low poly.
Now whilst doing normals in this way is magical and you get great results it's worth remembering that rarely do you get a perfect result from the projection especially around tricky bits of geometry as such a lot of tweaking has to be done by hand in photoshop.
To illustrate the point here are the normal maps straight from the projection and the one which I have altered by hand.