Gazebo, the kind you can erect on a hard surface, weather-resistant or rain-proof. 3 metres square would be ideal but we are open to offers!
Folding tables - not flimsy paste-tables of the sort that collapse in the middle though, as they will be supporting squash and marrows.
The committee are looking into buying both items for long-term use, so let us know if you hear of any going spare!