I have a book I picked up second hand
Britain's Shield: Radar and the Defeat of the Luftwaffe by David Zimmerman (ISBN: 9781445600611) Which goes into the establishment of the whole of the system not just the radar technology, not a page turner but a very well researched and annotated book.
There's a small part of a Chain Home Lo station visible as you head West towards Portalbot on the M4. You can just see it from the motorway westbound just after the Margam Junction.
Subterranea Britannica: Sites: