As usual it takes longer than it should.
I've got the small patch in floor pan welded in place. This bit was butt welded - I've still got to grind the welds smooth...
...I got fed up with all that weld - grind - weld - grind - weld and went and played about with another bit of bending and trimming for the larger replacement piece on the bulkhead.
I think I'm going to do a lap joint on the bit that will be inside the sill and then butt weld the bits that will be visible inside the wheel arch.