I am sure that people looking for advice are getting rather confused about now as to how much a house would cost to build.
Just to clarify, it is the same in every country, the price depends on where and what kind of house you are looking for. A master masonry stone built house in the centre of Athens, is of course more expensive than in the countryside.
Check out how much houses were sold for in the area you are thinking of building and check what standard it was when it was sold. This will give you a much better idea of how much it will cost.
You can hear horror stories here, like anywhere in the world. Do some research on the builders you are going to use, ring up previous clients of the builders and ask them how they got on, this alone could save you a lot. Alcohol is a problem but that can be dealt with contractually.
My advise is to buy a house that's already standing, the fact that you don't have much of a clue as to how much it would cost to build, leads me to believe that you are out of your depth.
You have probably heard stories that Mr. X built his own house for a small fraction of what the selling price is and think you'd save money doing the same. I don't think you will, shop around and see if there are any deals to be done on buying an existing house.
If you really insist on building your own house, you need to do a lot of leg work. Buying existing plans and having them modified by an architect, is probably the cheapest way to deal with the drawings.
Make sure that you have connections to water, sewage, electricity and gas (if applicable) BEFORE you start.
I was told I can only use 40% of it for the construction of a house; however, it seems it is different if I want to build a semi-detached house. Anybody can explain that to me?
When buying land, it is best if the local town council has a general plan (has designated the land for particular use), it is different in every place and many places do not have this, so you will have to apply.
You probably have it that you can build one building on 40% of the land plot but it can be divided into two semis.
Again I repeat, if you are asking such basic questions, buy an existing house, it will save you money in the long run.