I remember playing this on the Amiga way back and found it to run to a time limit, as in if you do not complete in a certain time the Orcs invade and "GAME OVER"

What caused the time to deplete for me was in the fact that I could not find the unicorn, I recall going to the place on the map where it was meant to appear but it never did, maybe I was in the wrong place, I never found out, after that happened I never ever played it again once I found out about the Orc invasion Game Over senario.

Now the game/games are here I am getting itchy to play again, but the above puts me off, did I miss something along the way in the game, or was the Amiga version bugged ?

Thanks, may go for it and give it another go :)

Usually the time limit should be absolutely no problem. You will reach the end of the game long before.
The unicorn does not have its own piece of the map. It will bring you the first one that is still missing. So you do not really need the unicorn. Just follow the information and you will get enough pieces.