Well Port Glasgow is like a lot of places that has affluent areas and other areas where you can buy a flat for £10000 but you’d need to ask yourself why
They will be in a shitty street that’s why they are cheap.
As for the land for sale I’d imagine that most of it will not have permission for dwellings, so you’d just be buying a bit of land that have restrictions on it.
So in answer to your question, no they will not be in nice areas.