It will depend on what a donor wants to give towards. I would happily donate to a charity that promotes a network of support for the elderly and their carers, which I understand used to be Age UKs main focus. If I donate now, I would have no say in any lobbying they do, and may not agree with it. Another example is people might support work Stonewall does to help LGB and T people who face homelessness, or are living with HIV, but who are aghast at their lobbying activities especially where conflicts exist with other protected characteristics.
My last visit to the National Trust was marred by the focus on LGBT. Lots and lots about one heir having to flee to Italy because of "misbehaviour" with guardsmen, virtually nothing about the sister who managed and refurbished the property in his absence. She too might be a worthwhile role model.
I agree that local charities can be a mixed bag. Wasn't Aimee involved with a youth group in the midlands well after the Green scandal. When I looked on the website there did not seem to be any obvious safeguarding policies.
However there are lots of good local causes. I am confident my regular donation to the local disabled swimming group will help pay for minibuses and for biscuits and ribena after sessions. I know that this weekly trip is important for a group of mainly house bound people. There are any number of other worthwhile local activities. A friend is encouraging me to join her in her weekly coffee mornings for her fellow disabled ex service people. I am not sure about the time but I can certainly give her some money.
In the end surely the solution is some sort of approval rating for charities, large and small, with focus on safeguarding, financial checks and balances etc. Sport England has a useful ClubMark certification for volunteer run sports clubs. Something similar.
In terms of overseas charities, is CAFOD ok? A friend is a strong supporter and it would seem to have useful links within Catholic communities overseas. I know that a lot of UN ones have very high operating costs and appointments are often very political.