You don't have to be in your twenties to be a night owl. My wife started line dancing in her fifties as a guard against balance and falls. Most nights we end the evening in the Yatch Club, dancing until around 1am.
Then on to the Lido, which is very much still open. It has mostly just drinks and whatever sweets are still available after dinner service completed, but there is slways at least one savoury dish still available.
I think that the Lido is open until 2am or 3am.