After a bit of a cleanup I was confronted with this:

Which I then gave the belt a good pull which then resulted in this:

Now the van has passed 4 MOT's in my ownership and I'm guessing this hasn't happened recently, so first of all I'd advise anyone to check theirs too and not rely on a garage to do it for you.
Onto my question, I'm guessing this will require a whole new panel, can anyone suggest a good quality replacement, preferably with a link please? Also any tips for welding it in would be appreciated. I'm aware the expansion tank will need removing but any other advice would be appreciated.