A somewhat belated update on how this went at the exhibition: we fixed some faults, and managed to run trains fairly successfully all week-end, albeit with some recurring derailments fixing which is top of our priorities list. Some other faults we could not fix at the exhibition and require more work.
Exhibition goers reacted positively to having a work in progress layout on display: many commented that it showed that a completed layout is achievable by showing an intermediate stage in the process from idea to fully formed and scenic layout. The exhibition also proved the concept of the layout, which, subject to derailments and electrical flaws, all fixable with some work, worked well, and there was much interest in the layout's postwar dockside setting.
Here are some pictures from during the exhibition: