Great job jezza, just shows what can be achieved when you set you mind to it..
Back in the good old days of "bonus" I could strip, remove the damged panel, refit a new one, seal and paint... all in one day! obviously it helped having a genuine panel and all the kit needed at hand, especailly a spot welder

I fitted one those pattern rear panels a couple of years ago, and remember having to drill the spot welds that attached the R/H rear lamp bucket as it was about 5mm out of alignment, other than that, I found the panel to be a pretty good fit
Jay, the dent in your rear panel is very easily repairable, as long as the seems are corrosion free, there is no point in breaking into them to replace the panel, using a large block of wood, and a few gentle taps with a sledge hammer would see most of the damage taken care of! Whether you knock the dent out, or replace the panel, you'll still end up filling and painting..
Thom