Lucky you going for a full month!
As has been said before, it really depends how much you're wanting to go out clubbing and especially drink in the clubs as booze in the clubs (and some bars) is not cheap at all.
If you do a search, you can see posts where this has been discussed and everyone has their own idea of how much you'll need. Some say you'll need up to £1000 a week others can get by on much less.
Last year, I went out clubbing four times (Carl Cox at Space which cost 15 euros to get in, Circo Loco at DC10 which was about 25 euros, Cocoon at Amnesia which was about 30 euros and Sundays at Space which I got in on the guestlist), drank only water in the clubs (water is between 6-8 euros and can't be refilled as the tap water tastes foul, although some stomach it, I don't know how though!), went out for lovely meals most nights and went to a few bars, hired sun loungers pretty much every day by Bora Bora and got taxis and spent £600 for 2 weeks.
But like I said, it does vary. Drinking booze from the supermarkets in your apartment or on the beach will save an absolute fortune, and also not dining out so much.
wonder how much will i acutally need for the month 
where ya stayin