I think the pictures below show what I spent the last two days doing in my garage. Although It wasn't exactly all day, I did get a lie in each morning.
I pulled the rest off the left dog leg/wheel arch off and removed the lower support behind the front jacking point, this revealed the hole in the chassis. I also ground the under seal away to find a few more holes and a couple of patches that had got me through a few MOT's in the past.
For anyone replacing the bulk head panel/back inner arch panel in worse condition that this you may need to notice the tab that protrudes down, (click on the first 2 photos below to enlarge) this rests on the top hat section that sits behind this bulkhead allowing for a small gap along the rest of this edge.
Cutting, forming, bending and filing can take up so much time, then welding, grinding and re-welding any holes then take up the rest of the day, giving you just enough time to spray on some primer before bed.
Tip of the Day:- the best grinding disc I use is the disc with the small layered sheets of abrasive paper, they are so much easier, faster, smoother and even a little quieter than the conventional metal grinding discs.
I had to put 2 Joggles in the lower patch Id made, the outer was easily made with the Joggle pliers but the inner was too deep for these. I don't have a set of joggle wheels so I placed two similar thickness sheets of steel either side where the form line was required, then held with tape I squashed them in the vice (a fly press would have been better) that had several layers of tape on the teeth to protect marking the panel. The result came out OK, I had to finish the edges with a mallet and block and I should have placed the sheets a little closer together. 
