What do I wear to winter wedding???

[YetAnotherNC]

Hello, I need some help! I'm going to a v v posh wedding next weekend, and haven't got a clue what to wear. Gentlemen are in morning dress and top hats.
Haven't dressed up for ages, and haven't been shopping either... I'm a curvy size 10, 5'6" dark hair, although not over endowed I do need good ...ahem...scaffolding up top, I quite like my calves and ankles, it all gets slightly wobblier above the knee. I love tulle skirts, rich colours, embroidery/appliqué, sleeves, midi or long length skirts, beading but not florals, I get very cold and hate sleeveless. I look pretty awful in most pastels. Anyone got any ideas? What do I wear as a coat/cover up for the church? Hats? Eeeeeeek.... Please please guide me in the right direction!!!!