After testing out various schemes to get the colour I want, and proposing all my cloth/cloaks etc to be Tartan, here is my Terminator Captain incorporating all the elements I have been toying with.

The Armour recipe I'm going with:

Base of Naggaroth Night (or Leviathan purple contrast)

Layer up with Asurmen Blue then Teclis Blue.

Highlights with Teclis Blue and Moot green

The Tartan is based on the Kilt I have which I can't remember the name of... Something Mist or such like.

Eshin Grey base, wide stripes of Abaddon black, thinner stripes of Incubai Darkness, then lines of Genestealer purple and white. Though I might use something less "in your face" as the white next time. And obviously practice freehand lining and use a thinner brush for the lines. 

The stone base is to give the effect of Edinburgh Sandstone (not covered in soot and grim!), and the Tyranid is my own scheme of black with green. 

His icon above his head is falling off, so I'll need to fix that (again!) or replace it.