The increased availability of GPS via cheaper GPS units, most modern smart phones, and even some cameras is a great help to getting accurate locations for records.
Using a GPS to get a grid reference
If you work entirely in grid references, many GPS units and phone apps such as GPS Status on Android phones can be set to OS Grid Reference format so you can just read off the grid reference at your location.
Alternatively, you can convert from the longitude/latitude to an OS grid reference afterwards. If you just have one or two locations to convert, try a web based conversion tool such as those from British Geological Survey, Moveable Type, Nearby or Ordnance Survey. If you have many to convert, use a batch online tool such as grid reference finder or a spreadsheet tool such as this excel add-in or the one from Ordnance Survey.
Boundary Downloads for GPS units
VC 65 North west Yorkshire (covers part of Cumbria around Sedbergh-Dent).
VC69 Westmorland (with Furness)
VC 70 Cumberland