There are many gowns designs that would be in keeping with this time period. The full length "A" line or empire waist line gown with a train would be work beautifully for this period. The sleeves are quite often long and the gown is usually trimmed with a rich ornate fabric trim. The brides of this time period wore their hair down with a simple "wreath" headpiece made from fabric or flowers. In some cases, the bride and her brides maids would hand pick the flowers in the morning and share in creating their headpieces together. A simple crown or one that is inlaid with jewels would also be quite fitting. It was also traditional for the bride to carry a white bible instead of flowers.
The bride’s maids gowns can be a simpler version of the bride, you can choose to have the maid of Honor in a slightly different colour from the maids with all of them wearing some kind of wreath headpiece. In some cases the bride’s maids would hold the bride’s train as she walks down the aisle therefore no bouquets would be necessary.
The groom could wear a knee length tunic with slim fitting pants or opt for the chain mail pants and shirt with a collar. A full cape would finish off the costume nicely. His head piece could be a crown.
The Groomsmen can be dressed similar to the groom. They could consider carrying a shield and or a sword. If swords are used, you may consider having them create an archway that the bride and groom can walk under at the beginning of the reception.
The flower girl can be dressed in the same style as the bride’s maids and her headpiece can be a wreath or a cone hat with a veil attached to the top. You could have her spread rose petals down the aisle.
The ring bearer could be dressed the same as the grooms men or you could dress him as a page (tunic, tights or form fitting pants with a floppy oversized French tam with a plume).