Colin,
In response to your question, basically no.
As far as the mains powered equipment in the van is concerned, it doesn't matter if the live and neutral are switched. Your fridge, battery charger, etc., will work fine with any polarity.
What is, or may be an issue, is the safety of the users.
In Europe all mains appliances switch both the live and the neutral supply lines, in the UK only the live is switched (a bit cheaper and dumb as anything). If you use UK appliances with a reversed polarity, then the switch only interrupts the power after it has flowed through the appliance.
Reversed polarity won't make something "live", but if you like fiddling inside stuff with the plug still in the socket - it could well be live.
We have a German Eriba, so every fixed appliance is double switched, and since most appliances are pan-European (Dometic fridges, etc.) they should all be double switched even in a UK van.
All of our mobile camping appliances (kettle, steamer, coffee machine, etc.) are double switched.
Robert