If you're interested in the Rosemary Caddy books, I'd get the essential oil one, but not bother with the blending one. I have it, but I prefer to make my own blends. I do like her blending calculator software though - you can put in your own blends, and get a picture of the chemical make up of your blend.
I swear by Julia Lawless's Encyclopaedia of Essential Oils, and Shirley Price's Practical Aromatherapy has top, middle and bottom note info.
Hope that helps.
Nellx