Hi Andy29uk,
I stayed in the Beni Beach last year it was also may, the weather was fab, couldnt fault the holiday at all but i think the apartment are more geared towards families! Didnt see no all girls or guys groups. The apartment all have the most amazing view accross the ocean. I didnt see much nightlife in that area just lots of resterants but for 4 euros you can go to the new town and i would recomend the square for all the nightlife or its about a 30 to 40 min walk.