Which membership organisation rules apply to your organisation
Membership organisations — trade and professional bodies, trade unions, religious congregations, political parties, clubs and societies — are mostly governed by the universal duties, with data protection looming large because membership records are extensive. On top of those, what you must register depends on what kind of organisation you are: trade unions list with the Certification Officer, political parties register with the Electoral Commission, and charitable bodies register with the charity regulator for their nation.