Do you mean cost in dollars to construct or the cost of having to live with a poor layout?

The layout isnt a concern at the moment as that would all be changed, just the costs to construct a house of that size so we know where to put our expections as we don't know what size house our budget would get us apx as we havnt built before.

(not a pro) The house size is only one factor of the expense to build. Other factors include the shape of the structure, size of the roof, types and number of windows, interior and exterior materials used, local cost variations, availability of materials and labor, basement vs crawl vs slab, the nature of the lot (slope, soil type, whether it's connected to utilities already, is it sewer or septic)... and so many others. Trying to guess what you can afford based on cost per square foot is not very accurate.

It's great that you have a budget in mind. Maybe some meetings with builders and architects will help you get more specific help.