I grow with exactly that hieght in my loft...you're not my neighbour are you ?

I run a 400 watt bulb and if I tie down and train my plants I can grow anything in there including full on sativas which stretch like buggery.Learning to train/tie/top or whatever method you want to use will be vital because with your height there are very few strains you could grow to their full potential without topping/training.
Have a look
Here for info on training plants.
You'd be well to start off with something Indica though to make life easier.You'll need at least a 100mm extracot, ideally a 125mm.Also you'll need to look at insulating the loft as it will be cold in the winter and hot in the summer.You'll need some kind of heating in the winter I suspect.
I''d say have a look through my diary in my sig but its pages and pages of random shit that'll be of little use to you.. my first coouple of diaries are
here and
Here ...they may be of some use...quite probably not though