This book has quite a lot of detailed instructions and information on the basics of candle-making, as well as essential oils. It also has quite a lot of sample projects to get you going, before you start coming up with your own ideas.
I've used this book a lot, and generally like it. However, I have two issues. Firstly, in some of the instructions it can be a bit vague when it would really help if it was more specific (so I have been referring to a second book) and some of it takes a slightly condescending tone in places.
All the "recipes" are either beeswax or soy wax. There is the barest mention of paraffin wax (along the lines of "paraffin wax exists but I don't like it, because it's not natural"), so if you want to use paraffin wax you would need access to another source of information for things like melting temperatures.
Good, but not as well set out as the bath bombs book, which (for example) has a table at the back summarising all the recipes and their ingredients, etc. I would have preferred if this book had that, so you could see at a glance which fragrances and colours were used for each.
It does however have a useful listing of places to buy your supplies (not restricted to UK).