As the ICO has updated its guidance to include the new charitable purposes soft opt-in, the Fundraising regulator has both indicated that it will shortly publish its own guide on fundraising marketing, and has refreshed its guide on data privacy. You can find out more at https://www.fundraisingregulator.org.uk/about-fundraising/resources/update-soft-opt-and-refreshed-data-privacy-guide.
It is especially important that you have clearly identified who is responsible for governance in these areas, and that they have the authority and resources to perform the role.
If you would like to hear about possible governance models, even for smaller charities, then get in touch in either of the ways below.