In the US, many States and Counties now have their own GIS Departments that make their data freely available on the web. This inlcudes LiDAR surveys! If you are doing work over there, just do a search for the local County Pages and have a dig around. Examples below:
Directory by State (hosted by University of Oregon)
If you're at a subscribing UK University: most Ordinance Survey data is avaialble via Edina's Digimap If you were to download just a few of these layers from a commercial vendor, it would cost you 100's to 1000's of pounds. This is an incredible resource at your disposal. You can find all the OS Explorer, Land Ranger maps, national, regional, county and local boundaries, digital elevation data, historical maps, geological maps, and much more!
Where data is only available in a NTF format, you may find the following conversion tools helpful for converting NTFs into DXFs or MapInfo Files.
Although the Ordinance Survey
is one of the major sources of elevation data sets in the UK, you can
not (that I'm aware of) download these datasets for free! They've sold
the rights to do this to a host of private companies (e.g. GetMapping). Fortunately for you, as long is you are at an
academic institution (UK only) you can download much of the data for free from EDINA .
Landmap provide a 30 m raster DEM for the whole of the UK (derived from Multiple passes of an ERS SAR sensor). You can download the data in 100 km tiles, or by defining your own boundaries. This resource is free to UWA students and staff.
The NERC Earth Observation Data Centre (NEODC) is a Designated Data Centre of the Natural Environment Research Council (NERC) and as such it is tasked with the acquisition, archiving and provision of access to remotely sensed data of the surface of the Earth acquired by satellite and airborne sensors.