you need about 6 months just to plan stuff out
there are loads of places you can go to see where this sort of stuff is on show, conventions and the like, but you need make sure the land you are buying will be able to get the planning to do what you need it to do

and watch lots of discovery real time to get you used to the fact that it might be 2 years before you are finished and you may go many times over your budget
they normally say that you should budget £100k for every £70k you have worked out
so if you have a budget of say £250k, you should aim to build around the £200k mark and have a bit spare in case things go tits up
£250k should get you a decent sized place to live in BUT this is all based on people building houses in fields they've bought for next to nothing