I did it! I have found myself a dressmaker. Or rather I have followed up enough of the dressmaking leads I had been given, to make a decision about one. Here name is Tanya Dimitrova, and today I went to her studio in Hammersmith. She's a fearsomly glamorous, well-groomed Eastern-European lady who used to work with Alasdair's 'Best Mel' at Karen Millen, before setting up on her own fairly recently. Mel recommends her very highly, and she instilled great confidence in me (despite being a little scary... it's the grooming!)
She briskly decided that the first stage was to make my pattern up as a toile (a mock-up made of cheap fabric), so she took my measurements (rather loosely for my self esteem) and I go back in about four weeks to try it on. She very much gave the impression that she could have the whole project finished by then, but said that it was best not to complete the frock til mid July, as "most brides, I find... most brides... they lose some weight" - she seemed uncomfortable, but I agreed fulsomely. I'm not sure she's had to deal with many brides my size!
So - the photos peppering this post are those I gave Tanya today, and between them suggest what's happening with the dress. I'm not sure I could be any more excited.