For the most part, Ireland isn't that far off of most metropolitan-type areas. Where I'm from, it's quite normal to see jeans and tee-shirts. Something maybe dressier to go to a pub or out with mates. I still have lots of friends and family there, so I know I'm not too out-of-style dressed when I visit and I live in tee shirts and jeans.
In terms of fashion design, I've recently developed an interest in Irish designs for bridal-wear There are some extremely beautiful designs reminiscent of more traditional garb, as well as many designers who take a far more modern slant.
Here are a few that I've found...
Celtia Gowns, by Mary Gristwood:
Brontë Bridal Designs:
Kathy de Stafford:
As you can probably tell, most use either traditional Irish Lace or Embroidery within the design, or something of a traditional line in the cut of the garment.
Actually, what I really love, that reminds me of princesses and medieval maidens, is the wedding cloak, instead of a veil.
Handcrafted cloaks and capes made in Ireland by the Siobhan Wear label:
I think, if made in organza or some other very light material, it ought to be light enough for the tropics...