3 metres by 3.6 metres?it tells you on the right of the field layout:
http://www.millennium-series.com/images/events/fields/london_2d_millennium-2012.jpg
Fixed!1.01 A playing-field is defined as being a flat, level area, surfaced to minimize injury and completely surrounded by league approved netting to ensure safety.
M7: 46x38 meters, at least 35 obstacles
D7: 55x33 meters, at least 35 obstacles
M5: 55x20 meters, at least 25 obstacles
Obstacles will be placed a minimum of 1.5 meters off the boundary. The playing-field boundary shall be marked clearly visible and will be placed a minimum of 1.5 meters off the netting.
http://www.millennium-series.com/downloads/rules.pdf