For heavier stuff the mig can't cope with, an inverter stick welder is handy and very portable, as already said, perhaps something like this:

If an inverter goes beyond the budget start looking at old oil-cooled arc welders, like an Oxford or similar makes. These are ideal for heavier farm work, but aren't exactly portable, they weigh from around 80KG up; mostly up.
If it has to be portable, and cheap, the jolly old buzz-box is always a cheap and cheerful option, but needs lots of practice to get good with it, and you have to give it time between runs, otherwise it will overheat.

You can run the 151EN and any other 150A max welder off a 13A domestic plug without any problems, apart from blowing the odd fuse occasionally when you do longish runs at 140-150A, or have it on a long extension lead that is too puny. I have run mine like this for over a year now, no probs. Machinemart and Clarke like to cover their backsides, is all.