You (yes, you) can find Roman roads using data collected by lasers by Barbara Speed.
Barbara reports that using Lidar data available from the UK Survey portal, David Rateledge was able to discover a Roman road between Ribchester and Lancaster.
She closes with:
The Environment Agency is planning to release 11 Terabytes (for Luddites: that’s an awful lot of data) worth of LIDAR information as part of the Department for Engironment, Food and Rural Affairs’ open data initiative, available through this portal. Which means that any of us could download it and dig about for more lost roads.
That seems a bit thin on the advice side, if you are truly interested in using the data to find Roman roads and other sites.
I can’t comment on the ease of use or documentation but LiDAR tools are available at: Free LiDAR tools.
See also my post on the OpenTopography Project.