Closure on this post...
For the boards I used 3.6mm ply from a local timber merchant, it worked a treat, I think original fitted was also 3.6mm but difficult to tell as I didn't have el vernier with me
I sourced vinyl covering from Vescom, type was Albert #1018.06
http://www.vescom.com/wallcovering_EN-- ... 83-1-0-202 The covering is excellent, not perfect match but it looks good fitted with the original.
Now here's the contentious bit, 4m of vinyl cost about £40, the recommended primer and adhesives cost me about £80 and the p&p was £25! The adhesives are only available in 10kg tubs hence so expensive. So vinyl was cheap enough but the adhesives were sky rocketing high. I didn't want to mess it up and didn't have enough knowledge of the product to be confident to deviate from the recommended adhesives and primers so I went for it. I like my van being near original and sometimes that costs

.
The primer is a 50% latex 50% water primer so any latex based primer will do that is 50/50. Do not dilute further. SBR springs to mind.
The actual adhesive was Vesom 1000, it doesn't work particularly well on this application, it takes 36hrs to dry and lifts at the edges. I folded the edges over and used impact adhesive on the reverse to hold them tight. Still some air bubbles on the edges in places where it didn't take, a bit gutted about this. Impact adhesive in the form I used (spray on no nonsense from screwfix and not really compatible with vinyl - something I found out after I used it) is too bumby and sticky (no margin of error allowed!) to be used on a facing piece.
So final verdict for those looking at this post in the future... Vescom covering is ace

need to work out a strategy for sticking it reliably
Anyone who is looking, I found this online a few days ago but not found anywhere to buy it from... 3M DI-NOC Weave architectural finish material, self adhesive.....
http://solutions.3m.com/wps/portal/3M/e ... 48700&rt=d
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