SuperTed,
I would tend to agree that its going to be near enough 40K.
If you pass every test first time, then it will be a bit less, but I would count it doing that.
When I was working out how much it would cost I estimated 25K......it actually cost 45K (and that doesn't include loss of earnings).
Its a bit like building your own house, in that it always costs more than you thought/budgeted for.
Good luck