NSPCC are in part an advocacy organization - of course they have high advertising costs. I don't donate to NSPCC because I don't wholeheartedly support the messages they advocate and I don't like the way they advocate. But faulting an advocacy organization for advertising is like faulting a hosptial for giving out medicine.
Secure recurring grants are very nice for organizations that get them. But a sensible charity should be looking for funding from a variety of sources - because different income streams are vulnerable to different threats.
Grants from endowment foundations are very vulnerable to stock market variations, large individual donations are often down to personal relationships with organizational leadership, recurring grants from stable sources are a great boon but generally have an end life and are hard to replace, government contracts are vulnerable to changes in government policy, etc.
In general, some of the most stable funding is individual contributions from people who volunteer with an organization. But that requires a strong volunteering and reationship building program (Ohh no! Overhead! How could they!).
It's not that any particular fundraising stream is wrong. It's just that people who are saying the OP should give to CiN rather than locally despite her misgivings over the organization's ethics seem to be basically saying "give to my charity not theirs". Which isn't very convincing for someone with no personal relationship with your chairty.