OMG WHERE DO YOU START

Seriously I have downloaded the guide from this site which is fantastic but can I ask if any of you have any good tips including any pitfalls we may come across?
We have to borrow 50% of the money we estimate it will cost us to build and the bank has asked for everything to be split up in small detailed spreadsheet which is a bit daunting as it means a whole lot of work now before we can even get started.
The short cut option of a contract with a builder is looking very appealing at the moment until I get my head round all of this.
Sasha
