As a further update, returning back to ICEM and as a general guide using this forum post.

I was able to create what I hope is a decent enough mesh of the rotating fluid domain for my purposes. I got the attached mesh report for the mesh. I've also attached the mesh file if anyone would like to have a look, but basically using Octree method to create an initial surface mesh, deleting the volume mesh, creating a couple of prisms with prism height limit factor set to one, then splitting these prisms and finally populating the rest of the region with Delauney tets seemed to have done the job for me.

Thanks for your help again nmpatre!