Thanks

Always have a much bigger contingency than you think you need.

never tell the builder what your real budget is

Always take as much time as it takes - throwing money at a build may not make it go any faster.

Always leave money unpaid until satisfactory milestones are reached.

Don't let trades write their own milestones, otherwise they walk off site with 90% of the cash for 50% of the job, and vanish into hyper space.

Leave at least 50% of the budget to cater for Her exotic tastes in hugely expensive fittings that will become absolutely essential to distinguish the new bit from everybody else's who has bought exactly the same high price fittings from the same Ditz Shoppe in the high street.