Creating Terrain from Level or Height Points

Hi All,

I have site levels (heights) for a project, and I am wanting to model the terrain. The project is a small deck off the back of an existing house, and there will be a lot of instances where we are doing small residential alterations through to medium commercial (e.g schools) which don't usually require a full geotechnical survey or contours, we have a level reader, zero it at the floor level and then take the readings of the ground levels around the building resulting in points.

What is the best way to model this, and then be able to alter it if we are excavating, adding retaining, flattening a site etc, and so that it can show up as a line when adding sections and elevations to the models and creating drawings? I have tried to find a tutorial, but the available information for how to do this includes complex georeferencing (which we never use) 

Would love to hear the methods for smaller scale terrain modelling and your suggestions, please see images added for reference to the said project. If someone could also add a step by step description/images that would be fantastic and much appreciated!

Olivia