You absolutely can do it. If you can work a set of tools you can weld. The mig welding website is a great resource (http://www.mig-welding.co.uk/) , with some good simple down to earth video tutorials on what you want to aim for. Of course welding can be a very complex, in depth subject (like anything can!) but welding on the thin metal that you find on a car only requires a small set of skills and criteria to achieve acceptable strength welds, so perfectly within the reach of the DIY'er.
Take your time, get a good welder (I reccomend the Clarke range, the 135te is excellent and good value too) get a decent sized bottle of CO2 / Argon mix shielding gas and a good twin gauge regulator (so you can see the bottle pressure and the flow rate) and do lots of practise on scrap metal. Don't be scared by it, small mistakes can be corrected such as blow holes, and worst case you can always cut it out and do it again!
Absolutely critical though is safety. As said above, a good autodarkening mask (I found weldequip - theres a link on the mig welding site - to be excellent to deal with ) and gloves, and good safety goggles for when you are doing grinding and cutting (oh, by the way a good grinder with 1mm cutting discs will become your friend). For goggles, go for fully enclosing ones, DeWalt do good value ones. DONT use safety 'glasses' as these allow debris to get in. When grinding / cutting / welding, don't allow yourself to become distracted by anything or anyone, if you need to divert your attention in any way at all, then stop and go do what you need to then return to it. You should always be pre-empting what could go wrong, particularly when cutting - such as a change from a thin skin to a bracket or thicker part, or a change in direction - could the disc bind up? Are you going to end up cutting close to your body etc, what way would the grinder kick back - try to make sure it is away from you! Just go slow and think it all through, and if you are not confident then consider what it is that is concerning you and try to address it rather than just charging on.
Plenty folks on here doing welding so plenty of advice is available as you go.
Edited by carlukemini, 26 May 2015 - 04:11 PM.