Thank you all, you are so kind. I am feeling very proud of myself for my newly discovered bargain-tastic shopping skills. The dress was £9, shoes £2, cardie £3, pendant £1, bag £3...and tights from primark for £2. So £20 all in. But without this thread I wouldn't have had a clue what to look for...and not just for the wedding, but for everyday outfits too.
So 
thanks so much everybody who ever posts a link or a picture of something.
I definitely can't take any credit for the figure mind you. I owe that entirely to BIWI and her incredible low carb boot camp thread, which has helped me lose almost two stone since New year. I am a different woman for sure.