Keep at it mate. Get yourself down the pub and beg a Co2 bottle. Failing that go to the local beer wholesaler (tons in the yellow pages) I paid £15 for my bottle, did tons of welding and emptied 3 kegs of beer as well. I went for gas and came away with the bottle and a keg of Fosters, then went back for another.. and another...
Anyway, good machine, good setup, decent gas bottle and auto helmet (makes it much easier) will get you there in the end. Go to the local college and see if there's course you can go on.
Its all a big learning thing and makes it all very satisfying when you finish the car. Peeps at shows are mighty impressed when you tell them you made it all!
Have a look on the mig welding forum. Tons of stuff on there for you.
http://www.mig-welding.co.uk/forum/index.php
LG,
Steve