Why not try a strapless dress like the one pictured below from Mango, currently on sale online at around 20 euros! Try the Alyson Fox clutch from & Other Stories retailing online at 45 euros and finish off your look with a Sensi Studio Hat from net-a-porter.com (around 90 euros).
Outfit details (worn by model): Cardigan from Zara, Dress from Urban Outfitters, Sandals by Sam, Hat by H&M, Necklace by Make a Wish