Most clubs do have a dress code usually casual that if it's a mixed bar and lounge area so anything goes like a towel or shorts as you mix with fully clothed people.
But others like Cupids in Manchester like you to change straight away from your normal street clothes into towels shorts or a skimpy sexy gear for the girls.. well it is a swinging club so you need to show everyone your intent !!!
best ring up first and check the clubs dress code