Airfix Magazine published a series of very useful and attractive guides from about 1974 to 1976. These were in A5 format with 64 pages in black and white, well illustrated with photographs and line drawings.
There were 28 in total: a full list can be found here on the Vintage Airfix site.
While the main focus (understandably) was on modelling, there were five wargaming subjects:
Ancient Wargaming by Phil Barker (the purple cover hasn't come out too well in the scan)
Others with a particular interest for wargamers are:
8th Army in the Desert by John Sandars
and (possibly) The French Foreign Legion by Martin Windrow
They were great when they came out: affordable, packed with information, robust, not taking up much shelf space, and much pored over. My favourites were the English Civil War and American Civil War titles.