As has been said elsewhere, fortunately the the worst thing about it was that MWK was right and the van didn't make it as far as the cambridge/essex border before breaking down. The second worst thing about it was that it stopped and refused to start again in the middle of a busy-ish roundabout (as in I was halfway through turning right so fortunately tucked nicely into the middle) when I was on my own.
I of course did the sensible thing and put the hazards on, hopped out to stand in the middle of the roundabout (whilst watching big lorries bearing down on poor Jules) and called Will who was fortunately not very far away. Before he could arrive though, three very nice men stopped their various vehicles and pushed me out of harms way and whilst I sat on the side of the road, two separate van owners, one in a van and one not in a van stopped for a chat and a nose in the engine bay.
As it turns out, my initial assessment of the problem was correct (a vacuum hose had become disconnected and I had no fuel going to the engine - slightly more guess work than actual knowledge but still not bad!) but I looked in the wrong bit of engine bay so didn't see the disconnected hose [Tech note: the vacuum hose to the air flow sensor had become disconnected so without the requisite airflow, the fuel pump cut out. I have been praised for my bug reports but need to work on customer led resolution - the first line technical support, as always, was first class... :) ]
With the hose reconnected, off Jules and I went again. Unfortunately we missed our lunch date but alternative company and a new location was proposed so we sat out on the edge of a field and cooked quesadilla's
thank you to Kathryn for the idea - I suspect they may become a common theme in van cuisine!
to complete our full van experience that day, we had fish and chips for dinner in a deserted car park near Burwell - not something which will feature so much in our budget foreign lifestyle but jolly tasty!
We have since had one further "refuse to start" issue - caused by a combination of points, timing and HT leads but nothing that couldn't be fixed with a cup of tea - and our first night on the road which was actually on a road (ie not a driveway) and life is all good!