Yay sponge!!!!!
Course you can buy morw chocolate. You need to thin it down for a fountain, with oil and/ or booze. Google for quanities. Cheaper chocolate works just fine. What a fab centre piece!!!!
Also, if you are going with the shabby chic thing, old bed linen make fab table cloths. You know, 70's ones or heavily floral, just lots of flowers. Bung them in the wash 90'degrees first though. Iron them and make sure you have the popper / button side the side people don't see. They will never know :)
Can you get a friend to Taje you at all?
Old bowls, plates are usually aplenty for 5p each too. And mis match vintage plates Will fit in so well with the whole shabby chic.
And don't buy bunting, its damn expensive. Buy old thibgs, bedding, clothes, anything with a nice pattern. Buy ribbon, or even string. Wash fabric, cut into large triangles. Fold over string and staple :) instant, cheap bunting..
My god, it will look fab!!!!!!