I have had so much help on here with the pics people post that I thought I will record and post this one properly. So here goes.
This is what this side of the van looks like now

This is a close up of what the rear panel looks like now

This is the sort of finish I am looking to get after having repaired (no where near as much) and painted the rear corner

This is what the inner arch looks like now

What I need to decide really is the sequence. I need to replace or repair the following:
Rear tall arch panel
Sliding door runner panel (many thanks in advance mm

Replace the sliding door runner cover lip
Remove and refurbish the sliding door runner (unless someone has one I can purchase)
Repair / remake the innner arch
I only have my drive to do this so my thoughts were do as much as possible before taking the rear panel off (i.e repair the arch). If I do this I will have guide to fit the new arch panel to.
Anyway that's the start. Will post more good or bad as I go