Full title: Allotment Gardening - An organic guide for beginners, by Susan Berger.
After 40+ years I hope I'm not a beginner, but this fine book certainly brings me up to date, and has useful sections on rotations, improving the soil and producing your own compost (either in a bin, or by using green manures to keep the minerals from washing away and feeding the worms and bacteria with fresh vegetation).
The gardener's calendar is very handy for making sure you don't miss the opportune moment for sowing easily overlooked crops/green manures, and for keeping on top of maintenance.
40 years ago, Lawrence Hills' 'Grow your own fruit and vegetables' was the organic growers bible. There doesn't seem to be a modern equivalent with the same detail about nutrition ... and Lawrence did get a few things wrong.
The BBC nowadays publish up to date information on healthy antioxidants and the like, to counter the misleading messages of the food corporations, and the internet can rapidly promulgate such helpful research to interested parties. For example superfoods the vitamins in common soft fruit.