Having built a similar build id say March is a bit ambitious, unless you are talking June next year :-)...... or youre a very hard worker.
Do you have a welder? If not you can get them for next to nothing over there in the U.S, teach yourself how to weld if you dont already know.... the welder will more then pay for itself if you can build parts rather then buying them...... then all you need is scrap metal and you can make your own tank. Its a lot of work but if taken one job at a time not very hard. And everyone here is helpful if you run into problems.
And if you do build it you will take greater pride in your ride, and i can guarantee you wont be able to wipe the smile off your face the first time, even if youre only going 20mph