I noticed the discussion previously about the type of organisation.
I understand Wiki v1 was a Company Limited by Guarantee and this proved to be a bit too onerous. (http://wck2.companieshouse.gov.uk/ea5e233643cbe7a39d43af65930f34fa/compdetai... shows the accounts and annual return were never filed)
As someone else has noted the Charitable Incorporated Organisation which simplified the admin side a little bit is not yet available.
The alternative is just set up as an unincorporated association. More details are here:
http://www.charity-commission.gov.uk/publications/cc22.asp#9
The main problem with this is unlimited liabilities - if you are a member of the association and the association has a dispute with, say a venue, they could sue any member of the association as they would be jointly and severally liable.
Has this been considered before?
Andrew