The Ordnance Survey Interactive Atlas (PC CD-ROM)may be of some use. Covers the whole of mainland UK at various scales, albeit in a road map style. However, it gives the ability to click on a start point and any turning points, giving leg distances and total distance (note: in Kms and statute miles only). It also gives the co-ords of the cursor in UK grid or Lat and Long.
Available from Focus Multimedia on 01889 570156