Add county to reports
Ah yes unfortunately you will need some PHP edits to make that work; Custom
reports in CiviCRM are a good way to start getting into the code base though!

Here's two references for you:
https://sf2012.civicrm.org/sites/default/files/slides/CiviCRM%20Reports-Customize%20and%20Extend.pdf

and

https://alastaira.wordpress.com/2011/03/17/civicrm-creating-a-custom-report/