I'm a working mum - what are good books I can get my helper to read which might have tips/ ideas for engaging games, activities for my kid?

How about this book from Gymboree? It is chock full of different activities that your helper can use to interact with your baby and engage his senses. There's a different activity for each day so there's no reason to get bored! I'm intending to get a copy for my dad so he can use it with my daughter. The activities are structured in line with their development. http://www.amazon.co.uk/Activities-Your-Toddler-Will-Love/dp/190582517X