She will also urge trustees "not to go for the lowest common denominator" when assessing their charity's activities ahead of the forthcoming public benefit test, although she will deny that the test will lead to "general culls" for particular kind of organisations, such as religious charities or those that charge fees.
She will say that demonstrating public benefit will not be a "tick-box exercise" either. She will say she hopes it will "lead to a raising of aspirations and standards across the sector".
"You need to start looking now at what you provide, how you provide it and to whom you provide it," she will say. "You need, in effect, to start asking questions. And when you answer them, can I ask you not to go for the lowest common denominator?"
She will admit the act also presents new challenges for the commission's board, such as raising public awareness about public benefit and developing the criteria to measure it, but she will insist the board is "well placed" to meet those challenges.
She will say: "It is a board which better reflects the diversity of this most diverse of sectors. In gender and race terms certainly, but also in terms of those who can challenge while staying strategic, stay supportive while criticising and steward resources while pushing the status quo."
She will also welcome the fact that commission decisions will be open to challenge in a Charity Tribunal.
"The ease with which our decisions will be challengeable can only lead to our greater accountability and the opportunity to develop case law further," she will say.