postition of greenhouse

Hi Rufus - well, basically, away from trees and as much light as possible. A path to it is a help.

Is your greenhouse to be a lean to or apex.
A lean to could face South and an apex North to South.

Hi, dont know what you intend growing but if its tomatoes, I would probably consider growing a grape vine along the apex as this will give a bit of shade from very strong sunshine through the Summer, my tomatoes have always done well in this situation. Also, tomatoes are sensitive to draughts from the door so I would avoid having the door facing north/east.

I find that having a greenhouse running on an east/west axis, means that all the plants inside get maximum sunshine from morn till dusk. Also, if the door faces eastwards, it doesn't get damaged by the prevailing west wind, which could blow in, damage the plants, or even lift the greenhouse up.