I managed to make some small progress with the insulation this week on the van.
I decided to go for the 2mm silent coat and 16mm Dodtherm as well as the recycled plastic insulation for the voids that I couldn't get my hands in.
I've only done the rear panels so far and put some pieces in the tail gate, I'll re-visit this when I get back on it later today. I wasn't sure at first if it made a difference but my wife's driven since and reckons it sounds less van like already so figure that's a good gauge that it's working!!!