Darren,
You may want to suggest the use of 'Grasscrete' products to form a parking area rather than the grassed area currently proposed by the council. It seems that the council can't budget for a 40 car tarmac area, but you may get some co-operation suggesting an alternative. Grasscrete allows grass to grow through and still allows a surface for vehicles to drive on. It's not too good if the area gets waterlogged though - which would have to be checked out. We use it for access roads on reservoirs etc where the planning conditions dictate that the finished appearance should look like a grass area. Hope this is of use.
http://www.grasscrete.com/docs/paving/index.html