Hi Guys,
Sorry that I posted and then never ended up getting back to you. Your posts were all very helpful, and I took them all on board. A good bit of help came from EHM-2155, so much thanks Mariano. I ended up talking about the economic, social and environmental impacts of the 3rd runway and possible terminal 6 expansion.
My teacher has marked it, but wouldnt tell me the exact mark. She said that the IBDP exam board will give it a good 'official' mark as well. I ended up concluding that the expansion should not go ahead, and that another London airport (such as stansted) should be expanded instead, or that London does what other major cities have done (Paris, Hong Kong) and move their major airports further out of the city. Apparently the essay was written from the view point of someone who wanted it to go ahead, to someone who wasnt so sure anymore. But it swayed my teacher into thinking the expansion of Heathrow was a good idea!!
Thanks for all your help,
Joshua
EHM-2309