Here's the latest on the saga of the broken van.
I organised its recovery today and it's now at a garage across town from me.  Renault, in their infinite wisdom, have quoted 5 - 10 days to get the new ignition barrel to the garage.  I think that's pretty disgraceful really - though I do appreciate that it has to be compatible with the current vehicle coding/keys and I've no idea of what's involved.  So ignition barrel and starter motor is the initial diagnosis prior to the garage having a more detailed look.  Obviously the starter motor can't be replaced prior to the barrel because it would probably result in another burn out.
As for the window becoming non-operational.  Ignore that.  That was me being silly.  I found out that it works perfectly if the ignition key is only turned half way.
I guess I will rent a small van for a few days.  I have enough contaINERS FOR 225 LITRES and a backpack to work from. Also I have a telescopic ladder if needed - though I would probably defer any ladder work until I get my van back.  Hardly ideal but at least I can earn.
I think it's ridiculous that Renault's slowness will cost me far more than the parts and labour.  It sounds like the parts will be a lot less than I originally guessed and the garage will be getting me a non Renault starter motor.