Do remember that there is a publication called "Folk London" (which I edited for over 10 years). If you do wish to call the event "F**k London" you should ask Sheila Finn first.

I would definitely suggest that you advertise in "Folk London" and I expect Sheila would be willing to print some details of the suggested event, if you sent her the copy. Sheila is involved with "Sharps" folk club and works at CSH which should also provide a further place to advertise the event.