I have a friend who did something similar to this but in his case he did it in his spare time (he works remote/flexible so spare can be during the day), mostly taking inspiration from guys like this that document the process and mistakes that they make or happen along the way.
He was fortunate to have a plot of land in the middle of the woods large enough to allow him to build what the law here defines as "support house" that can be maximum 26 m2 (most people abuse it). Another benefit he had is that his uncle owns a lumber mill just 2 km away and he could get wood beams and planks very cheaply and conveniently. For insulation he used mud and straw he got for nothing from nearby farms. After painting the facade you really couldn't tell.
