Do you know of any charity bank accounts?

Yes, there are a number of them and they include:

The Charity Aids Foundation provides the CafCash and CafGold Accounts– http://www.cafonline.org.uk/
Unity Trust Bank which provides the Ideal Current Account – http://www.unity.uk.com/
Co-operative Bank which provides Community Direct Plus Account – http://www.co-operativebank.co.uk/