A nightclub frequented by women of low standard who are out to show off there wares in the hope of a sly grope or of making out. These women are normally over 40 or under 18, and most would be mistaken for hookers if they were seen in natural light.
A cattle market is the sort of place that male first year undergraduate students at university go all the time in an effort to get their end away, but this invariably results in the guilty boys leaving the venue with an itch.
The term derives because the women in these clubs are essentially showing themselves off in the hope of being taken home, just as cattle are shown off at cattle markets in the hope of being sold.
Bill: "Let's go down Icon and Diva!"
Pete: "We can't go there, it's a right cattle market!"
"Ooh, I was in Creation last night and pulled this slapper - now I have an itch! Serves me right for visiting such a cattle market!"
"Let's go down to Gatecrasher - I hear it's a real cattle market down there!"