The detailed beta: sharper buildings, and a horizon model built to run on free Environment Agency LiDAR for measured heights, trees and terrain.
A model, not a survey. In its standard mode this beta builds the skyline from OpenStreetMap footprints, so heights may be estimated and trees are not included. Connect a LiDAR horizon service and the skyline is measured from Environment Agency LiDAR instead, folding in real building heights, trees and terrain (winter-flown, so summer leaf shade can read low). Either way, treat the result as a guide and check the spot yourself. This is the detailed 3D beta of the standard shadow simulator. For the saving in pounds, use the postcode calculator.