Here are some of the books I have found very helpful since I started the 5:2 diet: 
The 5:2 Diet made eZy by Polly Fielding
The 5:2 Diet Single Serving Vegetarian Recipes by Belinda Price
Your 5:2 Diet Days Tasy Recipes for One by Lucy Lonsdale
A new one I have recently downloaded onto my kindle which is really good for one of the 2 meals(the way I have just started doing on my low calorie days) :
Simple Healthy Smoothies for the 5:2 Diet by Emily Hanson

The 5:2 Diet made eZy by Polly Fielding
The 5:2 Diet Single Serving Vegetarian Recipes by Belinda Price
Your 5:2 Diet Days Tasy Recipes for One by Lucy Lonsdale
A new one I have recently downloaded onto my kindle which is really good for one of the 2 meals(the way I have just started doing on my low calorie days) :
Simple Healthy Smoothies for the 5:2 Diet by Emily Hanson