ARGH!!!!
Sodding weather! i've had one usable dry day since the test and now it just won't stop raining! I can make templates for the holes and cut patches to fit, i'm just a bit cautious about dragging the grinder and welder out into the raging deluge that never quite lets up.
bum
Angle grinder will be fine, and as long as where your welding is dry that is fine as well. Not nice and not recommended.. But totally usable.