I've just heard about this competition the local council are running (closing date June 19)...
http://www.eastlondonadvertiser.co.uk/content/towerhamlets/advertiser/news/story.aspx?brand=ELAOnline&category=news&tBrand=northlondon24&tCategory=newsela&itemid=WeED26%20May%202009%2011%3A52%3A47%3A580Now you might think it doesn't make sense for guerrillas to enter council competitions, but you'd be wrong. I entered my first as a 'front garden' (despite being on the 6th floor) and won a commendation from Southwark (it wasn't for two more years that they discovered the garden was illegal) and at that point their certificate made it a little more difficult for them to turn my request down. And you might even get some funding!