I have started a Square Foot Garden in front of the shed in my back garden - the space was just covered in lots of pots and it gets the most sunlight.
It didnt take long - my two sons helped build the boxes and then using an American guy's book (Mel Bartholomew) put in compost, peat and vermiculite. Then over the top of the frame you put a grid and just plant in the grids. One plant per square foot - depending on the plant e.g radishes x 16, cabbage x 1.
I'm really looking forward to eating my own veggies this year.