Seriously, it's a bit of an ambiguous question isn't it?
It depends on so many things, like whetre you are, architects design, planning permission, materials used, and more to the point, nothing said on here could be definitive could it.
'Timber house' - what do you think you mean by this - timberframe, log cabin, Huffhaus from Germany? There are so many types with prices to match.
How are you going to get it built? - you as project manager employing sub-contractors or a General Builder to take care of everything.
To give you a very rough idea, a conventional timberframe house clad in nice brick with a decent roof of 250 square metres gross floor area might set you back �250k. It is not cheaper than conventional build.
That's just the house - then add on the land.