Finding the exact place or places where the Diary was written would be a major achievement. The few place names Anne mentions are the large towns of Hereford, Gloucester, Chepstow and Telford. Telford is a new town named after the Victorian engineer and didn't exist in Anne's day. It might be a mistranscription of Yelford which did, but that's in Oxfordshire.
We next turn to the farms and fields Anne mentions by name. The trick would be to match the names of farms to the names of occupants mentioned by Anne, but first we have to locate clusters of these names within a small geographical area. It's quite a task, yet several such clusters have been found in several areas, including Herefordshire, Gloucestershire and even south of Birmingham. The problem is the usual one, that if you want to find locations you can always find a few that seem to fit some of the criteria. However, there is one location that might well be the favourite. That is the area of Herefordshire next to the border with Wales and the Black Mountains.