For bodywork getting a LOW current is more important ,many small ,hobby MIGs dont really go low enough .20 amps would be ideal but 30-40 is more likely and perfectly good .Most people focus on MAX power of machines when its the min thats more to the point in auto body work .Prep and technique can get round heavier welding situations and the mig welding uk forum already mentioned will show you that .Or a cheap buzzbox stick machine if you like/need for heavier stuff if not .
Look for a welder with a "euro torch" ideally ,theres loads of transformer MIGS collection only on fleabay so look for a good name used unit close to you .If buying new on a budget look for an italian made welder rather than chinese or not stated and think about replacement part availability .Transformer welders are tried and trusted and easier to repair ,inverter welders are great when they work but the cheap ones....well....
All that said ,after years of welding and repeated theft of quality machines Im back with an ancient Clarke 100 hobby thing but with care ,technique and practice good results can be had even if you do have to flap-disc the welds back to a tidy condition ,
On the gas front theres loads of independent suppliers these days that are less of a commitment than a BOC contract .That or a friendly publican or soft drinks supplier for straight CO2 ,not such clean welds but theres always those flap discs...
