Thanks Jimble for the prompt on where to look for Postcode entry. It is great that I have now found where to enter the Postcode,
I can now confirm you can enter Postcodes on Nav Pro. Those of you getting Nav Pro can stop the cold sweats on whether you should have purchased it, all is OK now thanks to Jimble showing us the way.

It's a bit backward where you enter it though. Rather than just entering a Postcode as a single function. It requires you to go in to the address entry screen and then select the Town entry field, this then in turn as Jimble say's brings up the Postcode button bottom left of the screen. On this screen you enter either Postcode or Town. A bit weird and awkward to find for a noob. But all is great and wonderful now I know I have not wasted money on my Nav Pro. I can vouch to anyone getting Nav Pro it is a great piece of kit, just some options are hard to find for the first time.