Yes, as Maria says we meet every two weeks, changing the day in the week so that everyone can at least make one of the meets if they are working part time for example. We often meet at the Horniman, but our last meet was at the Plough for example, so its worth checking the slingmeet calendar for details of the venue.
So dont worry if you cant make this Friday's meet, and yes it will be busy at the Horniman (!), there are plenty of other opportunities to come to a slingmeet.