Hey jhaydock!
Starting to look good man, you'll get there!
A couple of tips... Lt Jim if was right, tone down the highlights just a little bit and you should add a bumpmap to the specular layer as well to break it up a bit. This will add some more randomness to the whole picture. I get a feeling with the DOF that its almost shot with a macro lens, less is more
To give the picture a bit more depth set up a standard env.fog shader, this will also tone down the horizon line! Also, on top of all the layers try and add a bright bluish solid color set the transparancy to 10% or something and play around with different blend modes.
Part from that, just keep playing around with different settings and dont be scared to go crasy with stuff, thats when you learn and finally find a balance.
Keep it up!!
/Chris
Beauty is worse than wine, it intoxicates both the holder and beholder - Immermann"