Remember that the outfit you arrive in will be available too.
Travel and arrival:
Trousers / jeans
T shirt
Wool sweater /cardigan. (Wear or tie around shoulders / waist.)
Smart raincoat or flexible jacket.
Evening:
T shirt dress (foldable fabric). Add same sweater or outerwear as relevant.
Next day:
Same trousers / jeans
Second t shirt / vest
Same knitwear / outerwear, layered as appropriate.
Evening:
Second foldable mesh / silk / cotton dress.
Return:
Whatever’s most comfortable.
Something like that? You don’t have to think about what’s fashionable - just pick a fashionable shop or two, like
American Vintage
Zara
Skims
Cos
Massimo Dutti
Realisation Par
Uniqlo
Asket
and pick out some lightweight, easily packable pieces that all work together. Try to pack a variety of fabrics - wool, cotton, silk - to make interesting outfits. Plus rainproof outerwear. Done!