How to earn £30000 quickly and legally...

Like the title says, I am in need of £30000 in order to purchase a parcel of land, which i would like to build my own home upon. Now bear in mind that i squeak when i walk because i utterly despise spending money. After seeing some "earthships" being built on youtube, that is my plan, i know i can get an abundance of old worn out tyres that i can use for my walls, i know i can get wood and lumber for free, and i know i can grow my own food.

My only problem, is the same problem most people face, i do not have the capital to just go and purchase the parcel of land.

Other than standing on a street corner and trying to sell myself, i am at a loss of how to get my hands on this amount of money.

Any red hot tips for the GeeGee's floating about?