How easy is mig welding, i've got a few jobs that need doing on the car and was wondering if i should pay someone to weld the bits for me or buy a mig welder for myself to do it

If you can weld get one and do it. If you've got to learn get someone else to do it, 10 to 1 you'll just make the holes bigger and frustrate yourself at the same time. I've done lots and it always starts with, "I've got a couple of little holes it'll only be a ten minute job" and when you get back to some reasonable metal to weld to and grind it clean the hole has grown that big it would be easier to replace the panel.

There are 2 important points with Migs.

1) Buy the best you can. The better ones have smoother wire feed and better arc control.

2) The most common mistake is lack of penetration. Turn up the power high and pulse the welds. To start with do lots of spot welds. This means you can position the torch accurately before each weld and get good penetration without burning a hole.
As you get better just pulse the torch, this allows a little cooling between each weld.

John

I learned a neat trick at the local college - nylon-tie a compressed air nozzle upside down to the top of your MIG gun.

The procedure then is to weld a bit with your trigger finger, then immediately blow it cool with your thumb. If you get good at it, you can actually shrink the weld pools while they're hot (less grinding later)!