What's "super-spud" ?? WTF?

You won't need 600w for seedlings. I use a high output fluorescent unit for my seedlings/clones/vegetative growth which is 110w and it works great, it's called 'light-wing'
If you live in manchester then I'm surprised you've never heard of Holland Hydroponics-
http://www.hydroponics.co.uk it's in the city center, good shop.

Don't be worried about light leaks if you use a HPS, that's an easy problem to sort out, just block all the places where light can get out with duct tape or something.
They aren't that expensive to run either (if you only have one or two small-ish ones!) And they are by far the best lights for flowering, you can flower with fluorescents but the results will only be a fraction of what you'll get with a HPS.
Take a look at the fluorescents on the site above^ or if you're on a budjet you can use normal fluorescents like shop-lights or compact fluorescents but they're not as good.
How close are your neighbours houses to yours? Will they be able to hear your fans?
Will they be able to smell the plants when they're in bloom?