I am planning an extension to our home and, since reading the book, realise how many holes I could fall into!
the book is very clearly set out and indexed, starts at the beginning (when your extension is just a vague idea), and takes you step by step through the whole process. It is illustrated with very clear diagrams and graphics, and uses non-technical language to put across stuff you never even thought of, but which is crucial to seeing your dream become reality.
There are lots of checklists that tell you what to look out for at each stage of the work, so you know how to keep abreast of what Bob the Builder is up to (or not up to, as the case may be).
When I asked the first person who wanted to do the job if he was "Vat-registered", his sharp intake of breath was a revelation!
Don't spend a penny on that extension till you've bought a copy. It could save you thousands!