i built a 10m Schionning power cat,took me 4.5 years every weekend 2-3 nights week and all my holidays (also used some labour for quite a few months) #-4000 hours was the quoted time to build, it actually nearly took 6500 and this is only half a 45 ft cat. i had a shed on an acreage about 10 mins from home and that was a bit of a pain, but at least no dust at home, this is a large undertaking and frm Bray park you will need to talk to mainRoads and council to find out what road works are expected on your propose launching route
(mine got changed as a new road was built with a bridge that i had to go under, in the end i put mine into a nearby creek at a very high tide and floated it out to the sea that way.
time to build varies a lot depending on the boat design and whether you use kits etc just remember you need a lot of room around a boat to paint
and work on it allow for an area to construct items, i had a shed double the area of my boat and that was tight. also the shed needs to be high enough inside so you can work on the top of your boat.
i built mine and worked full time, wife did all the mowing etc at home, and ran meals
etc to me most days so i could spend as much time on the boat as possible, it also took a lot of time getting materials ,windows hatches etc etc etc, boat shows are good but you need to do a lot of legwork, also think about getting a surveyor
to look at your boat at different intervals so that on completion it is easy to insure or more importantly a future buyer can confidently purchase
an owner built boat and know it is built correctly
Good luck with you venture whichever way you decide, it is a big task but doable. Cost me around 30% more than i though mainly on extra labour to help and stuff i didn't hnow about before i started.