Regarding dress code,
For the everyday teas, available in the buffet area, you should dress as you would for either breakfast or lunch in this area. Rougly interpreted, the buffet area rules are "you are not supposed to be dripping wet," and "wear a coverup over your bikini." This second rule is for the benefit of us old guys who don't want to choke to death from gasping and inhaling a chunk of food as a pretty young thing walked by. Do not get mad at me for this comment. I am not a sexist, I am just a DOM (dirty old man).
For the grand tea, served in the main dining room, again observe their dress rules for breakfast or lunch. No tee shirts or swim suits.
The daily "formal, informal, casual" dress code doesn't apply until 6:00 pm. The teas are over by then. For the grand teas, the staff dress code always exceeds that of the clients.
Les