As the most recent publication about The Goon Show, this book covers all the areas you need for a good overview. It contains background information, scripts, photos and an episode list. It also contains memories of the then surviving cast members - Spike Milligan, Harry Secombe, Eric Sykes (who wrote some episodes) and Max Geldray.
It's true that much of the book has been covered in other publications, but I think this is the most readable and if you are new to the Goons I would say this is the book for you. If you want a more indepth appraisal of The Goon Show and it's development you may want to consider 'The Goon Show Companion' instead.