Hey bro,
When I was in UK, i used to attend parties organized on a regular basis by a couple. She is called lady marmalade. You can check out her website -
http://www.ladymarmaladeparties.com/
The last time I was there, they had 3 sessions, 2 hours each session usually 2 shots for those who can make it. The contribution which includes wine and hosting is 140 quid. They had a total of 7 girls with a ratio of 2 to 1. So maximum of 14 guys per session. They are not the only one hosting this kind of parties in UK, there is another one called sacred rose parties and others. I have been to Sacred Rose and Lady Marmalade both are great hosts. I could never find something like this is Sg. I assume the ratio and girls would be the same and the charge is about S$140 per person.
http://www.ladymarmaladeparties.com/schedule
Hope this helps