How would I go about this? Anyone got any massive needles?

Oooh, I'm so tempted to do my first bit of post deletion :D .

No, sweetie, you can't knit a house. You can buy large needles (http://photos1.blogger.com/blogger/4238/1041/1600/knit1.gif), but nothing quite that big.

Any other questions?

You don't need massive needles! i've found a pattern (http://www.knitting-and.com/knitting/patterns/afghans/ourhouse.htm) for you that uses only 4.5mm needles! :D Enjoy!