So I decided to get stuck in. However I'm not sure if I'm using the best workflow.

Any advice/pointers would be welcome.

I was originally considering creating a height field map in ZBrush as I needed an accurate map.
I decided to create a height field map in Photoshop first, just incase. I then imported the height field map into Terragen as a TIFF. After right clicking on Terrain node group I selected Create Shader/Displacement Shader/Heightfield Shader.
[attachimg=1]
I was pleasantly surprised to find the map has dropped onto the preview canvas. After getting my head around the camera setup I finally saw my first render. It was very spiky, so I returned to my gray scale map in PS and introduced a little blurring.

[attachimg=2]
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I eventually got what I was looking for, but I need some help - By re-linking the nodes (see attachement) I managed to get some mountains in the background, however is it possible to but the mountains up against the rear and left of my height field map?

As you can see from the attachment (TOP VIEW) there is a beach each side of the headland, so how do I introduce an ocean here?

[attachimg=4]
Thanks to any one who may show any interest...