Could anyone point me in the direction of a map of pillboxes and stuff please? I found a site that has some but not all.
Define 'stuff'
Steve Thompson's gargoyle overlay (as mentioned above,
http://www.pillbox-study-group.org.uk/links/downloads/) is OK for things like pillboxes but doesn't include Cold War. For Cold War era structures then the database section of the SubBrit website (
https://www.subbrit.org.uk/ look at the menu for database links) is probably good...no direct download of all the points but it's easy enough to do.
The overlay doesn't specifically include airfields though those are effectively included now by the proliferation of Stanton shelters, dispersals and blast shelters on airfields. For more detailed info about those then the Airfield Research Group bulletin board may be a good place (but unlike 99% of sites built from freely given user contribution they now charge for access).
There are some excellent reports on here about specific places, specific Stop Lines etc., some of which include maps. Many Counties have a public online GIS and the more enlightened include HER layers and choices of base such as aerial photos from the National Surveys, their own local aerial surveys and assorted maps.
NLS have the contract to digitise a lot of old OS mapping....many of these maps include useful info even if purpose isn't necessarily marked (so many PoW camps, airfield buildings etc. can be identified). There are also old maps available from commercial systems ...which will allow you to look in detail and screengrab rather than purchase - easy to keep doing that for an area and then stich the images to get a bigger coverage.
As for anywhere having 'all'......doubt such a thing exists.
I can't remember the numbers off the top of my head but the original Defence of Britiain Survey, who's data Steve's overlay started from, had say 20000 placemarks...with user input since Steve started adding to that there are probably more than double the original and 'new' remains regularly found/added.
Going away from military there are overlays for disused tunnels, railways, stations, detailed canal maps etc. all available for free online