In essence all you are doing is submitting evidence in support of a planning application. Private firms do this all the time for private clients. I would question whether you need to submit a planning application for a change to a private residence. If the change is a material consideration (ie:- Does it raise the value of your house? Will it have a detrimental effect to third parties? etc.) then you will need to submit a planning application. Send a request in writing to the planning department and ask for them to send a council officer to survey your proposed change, or go into the department and request a meeting with an officer from development control.
Try to get hold of a scale plan of your property. These can be obtained from most public libraries. Maybe this is what the planning department is trying to get you to pay for? I am not sure of the details of what they are asking you to pay for. The Ordnance Survey requires people to have permission to use their plans. However, I'm not sure where a member of the public would stand with having to pay for use of the Ordnance Survey maps. I would suggest that you check this first. For a private planning application you could draw the extents of your proposed fence by hand. Ensure that it is accurate and to scale, showing the before and after situation. The distance of the fence from the property will also have an impact. The development control department will have publicly available policies on what is allowed. This should conform with national and regional planning policy. These documents should be available on the councils website. If you submit plans and an argument that does not contradict current local planning policy this should be enough for the planning authorities development control department to assess all the possible issues with your proposed change.
Other than that, a new fence isn't exactly a new Tesco store so I wouldn't worry too much. The planning authority should send an officer to assess the application on site so it's really their responsibility to ensure that the information in your application is accurate.
Good luck with the application and hopefully you will be enjoying your new fence soon! This is only advice and this only represents my current understanding of current planning procedures and policy.
Jamie (Kate's son)
Hope this is helpful ..
Kate >>> x