Good hats can be hard to come by, so if you see one, don't hesitate. Or scout out a local milliner for a custom-made option.
This year, Royal Ascot released a great style guide for those entering the Royal Enclosure. It perfectly sums up what dressing for the races should be.
Here are their formal day wear rules for ladies so you can do what the Brits do so well:
Dresses and skirts should be of modest length defined as falling just above the knee or longer.
Dresses and tops should have straps of 3cm or greater.
Jackets and pashminas may be worn but dresses and tops underneath should still comply with the Royal Enclosure dress code.
Trouser suits are welcome.
They should be of full length and of matching material and colour.
Hats should be worn; a headpiece which has a base of 10cm or more in diameter is acceptable as an alternative to a hat.
Ladies are kindly asked to note the following:
Strapless, off the shoulder, halter neck, spaghetti straps and dresses with a strap of less than 2.5cm are not permitted.
Midriffs must be covered.
Fascinators are no longer permitted in the Royal Enclosure; neither are headpieces which do not have a base covering a sufficient area of the head (10cm).