I think it would be great if you would allow societies to open an account. Many not-for-profits are registered as societies rather than companies. Societies are corporate entities registered on both Companies House and the FCA Mutual Register. In terms of anti-money-laundering regulations they are no different from a company. They have shareholders (on a one member, one vote basis) and a board in the same way of as companies. There are no additional compliance requirements beyond operating a company account - people are just less familiar with them.