A civil engineer can offer advice on all aspects of the house design
A Civil Engineer, in fact, has nothing to do with the design of housing. If you have little or no experience of self building, the best advise is research, research, and research.
You could arrange to meet with an architect to discuss your ideas, feasability, planning, budget etc. If you can be recommeded an architect then all the better. I would suggest that only somebody who has exstensive knowledge of self builds would go ahead without the use of an archtect.
If there have been new builds in your area of a similar size and style to which you would like to build then it is well worth trying to contact the owners, just to see if they have any recomendations or even warnings about builders, archtects etc.
It can be an option to employ a structural engineer with professioal indemnity insurance to deisign the house etc, thay can also sign off for mortgage stage payments, as with an architect. But the insurance is the most important point here. Your mortage lender will require copies of the certs in both cases.