I reckon the first question to ask is are you talking about spot welds or tack welds? If you're looking at a tack weld...an angle grinder or die grinder either one will likely be the best choice...even better often than a torch. Some tack welds are postioned such that you can get to them with a reciprocating saw. Beyond that you may be looking at some time with a cold chisel and ball peen. Hopefully this gives you a few possibilites given your space limitations and gets you going...I know outfits don't leave us a heap of wiggle room for doing stuff like this

Jim