I have a 115v welder and it can weld up to 3/16". The 115 welders will work just fine for doing bodywork.
With the 115 you can plug it in to any 110 outlet and it welds holes in body panels and spot pieces in . I would advise on getting a gas bottle for the welder. The gas will give you better welds. I know some say you can use a flux core wire without gas but I never liked the welds you get .
When you weld sheetmetal, you also want to use a small diameter wire like .023.
And when you get everything you need.....................just practice, practice, practice on old sheet metal till you get the settings correct for what thickness you are welding.