Bulkhead rot

Off roading last weekend and noticed water coming into passenger footwell when wading in deep water. Bit of investigation reveals a small hole smaller than a 2p in bulkhead just above the join with the passenger footplate. Two questions;

1. Can this be welded? I assume yes but its quite thin metal and in an area with a curve around the geabox so might be tricky (not that I know anything about welding!!)
2. Does it need to be done before the MOT or will it fail with this small hole in bulkhead?

Thanks

Popular repair on ere is a small patch weld chopped out from a biscuit tin.