Pill box hat, perched demurely at an angle, with a veil coming over your eyes. You have to have a fancy up 'do as well for the pill box hat to nestle amongst your curls rather than it just sitting there looking like a head pimple.
Colour-wise, you could do white, or navy, or the featured blue in the dots. Depends what you can find. I am the veteran of serious hat shopping last weekend, and there ain't a lot left out there apart from gold, black or pink, it seems. Everyone stripped the shelves of other colours in April, apparently!
I found a gorgeous hat in Hoopers in Tunbridge Wells - they have a large occasion wear department. You may want to google 'Occasion Wear' on Google Maps to see if there are specialist shops near you. Otherwise hit the big department stores. No good ordering over the internet, as it could look totally wrong with your face once you try it on.