As Octo says, the only reason we both suggest the 90 Amp Clarke machines, is because they do have a good reputation on here for welding quite thin metal. They will go down to 24 Amps, which is a bit easier to weld with on thin metal, all things being equal.
The 100 through 160 series go down to 30 Amp output, so need a bit more skill, which comes with practice, on the same thin metal.
As the model number goes up, so the weldable thickness of metal goes up, so the 135 welds thicker metal than the 100, the 150/160 series weld thicker metal than the 135. Up at the top the 160 series have the same 150 Amps output as the 150 series, but may be wound differently, because a slightly better duty cycle is claimed.
Be wary of Clarke's top metal thickness claims, however. The 90 series will not weld above 2-2.5 mm in one unprepared pass, see here:http://www.mig-welding.co.uk/clarke-90.htm
This test shows the 90 series cannot manage 3 mm, let alone 4 mm.
The 150/160 series are variously claimed by Clarke to be capable of 4, 5, and even 6 mm. On an unprepared butt joint, this is highly unlikely. They will manage 4 mm on a shortish run. To weld thicker steel, the metal would need to be prepared with a vee'd joint to enable sufficient penetration.
Any of the Clarke series with the letters EN in the model name have the capacity to also use flux-cored wire, which is more difficult to use on thin bodywork but can be useful if you work outdoors much, repair steel fencing or garden gates or outdoor brackets, etc. And on bodywork if you get good enough with them, eventually.
If you are repairing vehicle bodywork you should really be using metal the same thickness as the original, not thinner. If a patch is much thinner it will act as an anode to the thicker metal around it, and rot out first.
The 100 through 160 series go down to 30 Amp output, so need a bit more skill, which comes with practice, on the same thin metal.
As the model number goes up, so the weldable thickness of metal goes up, so the 135 welds thicker metal than the 100, the 150/160 series weld thicker metal than the 135. Up at the top the 160 series have the same 150 Amps output as the 150 series, but may be wound differently, because a slightly better duty cycle is claimed.
Be wary of Clarke's top metal thickness claims, however. The 90 series will not weld above 2-2.5 mm in one unprepared pass, see here:http://www.mig-welding.co.uk/clarke-90.htm
This test shows the 90 series cannot manage 3 mm, let alone 4 mm.
The 150/160 series are variously claimed by Clarke to be capable of 4, 5, and even 6 mm. On an unprepared butt joint, this is highly unlikely. They will manage 4 mm on a shortish run. To weld thicker steel, the metal would need to be prepared with a vee'd joint to enable sufficient penetration.
Any of the Clarke series with the letters EN in the model name have the capacity to also use flux-cored wire, which is more difficult to use on thin bodywork but can be useful if you work outdoors much, repair steel fencing or garden gates or outdoor brackets, etc. And on bodywork if you get good enough with them, eventually.
If you are repairing vehicle bodywork you should really be using metal the same thickness as the original, not thinner. If a patch is much thinner it will act as an anode to the thicker metal around it, and rot out first.
went out today and bought a clarke MIG90EN and all the stuff needed for gas welding , unfortunately I was given industrial 0.6mm tips - so Im practicing gasless for just now 
