I did manage to get in after a few attempts. The products available are
- MiniScale (raster)
- 1:250000 scale colour raster
- OS Street View (raster)
- Boundary-Line (vector)
- Code-Point Open (think this might effectively be the postcode database)
- 1:50000 scale gazeteer (just POIs, I think -- not the maps)
- Strategi (vector, not sure what this is)
- OS Locator
- Land-Form Panorama (3d vector data)
1:250,000 is the standard road maps that are what you get when you zoom out on MemoryMap. What used to be good cycling-scale maps before the OS stopped printing them.
The ones at work are 100kmx100km, 4000x4000 pix tiles (iirc), as tiff.
StreetView is the most interesting. It's a simplified version of the OS 1:10,000 raster mapping. Streets, (named, at a standard rather than actual width), simplified building outlines, areas of woodlands, watercourses etc. It should come as 5kmx5km tiles, aligned to the OS national grid.
It's machine generated from the detailed
MasterMap database (<1m accuracy), so road centrelines, watercourses etc will be accurate (possible easter eggs excepted). Buildings will be approximately correct, but you couldn't trust the detailed shape of a building (eg will be a simple rectangle, whilst detailed mapping would show the bay windows).
Boundary Line is county/parish/ed/ward/ua/constituency etc boundaries
CodePoint is just be an OS grid ref for each postcode.
1:50,000 gazetteer will be text and grid reference for each significant text item that appears on an OS 1:50,000 map. (including eg "Lower Southfield, Bosbury" or "Woofields farm, Coddington", but not stuff like "Hall", "Moat"). The ones we have aren't precise, just giving the correct 1km grid square.
Strategi is (I think) simplified stuff meant for large scale display - highway network, rivers, towns etc.
Locator as supplied to paying customers is POIs - doctors surgeries, categorised shops, banks, filling stations etc, It seems that they are only giving out road names/locations for free.
Landform Panorama is 10m contours. It is supplied as a DTM on a 25m (iirc) grid, but that doesn't seem to be included in the OpenData.