You've got to the point of working on a planning application and realised that you need to put in with it some reports and surveys.
My advice - shop around, but definitely go with a professional.
I come from a techy family, and live in a techy household, but the demands of the (fantastic) program AutoCAD escaped us all. It was necessary for the topological survey and reports on arboricultural and tree protection. So we went with a professional. Why spend time trying to do something that you plainly cannot do!!