Her weekly meetings continue and she now has a shopfront display that will become an information booth ahead of a school strike on September 20.

And the 12-year-old's efforts have "absolutely" gained the support of Tamworth-based Uniting Church NSW/ACT moderator Simon Hansford.

The church synod had resolved this week it would speak and act to support the nationwide student rally, saying it was "the first major institution in the country to give such an endorsement".

Reverend Hansford told the Leader climate change was "one of those challenging issues where a range of approaches are necessary".

"I think young people calling our attention to this is a critical voice in the life of our community," he said.

"We have to attend to our young people.

"Historically, we say, 'What do they know?' The answer is: they know a great deal."

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Reverend Hansford said, however, he was "not telling people or schools what to do"; it was up to children and parents to decide.

"I would not want in any way to interfere in that process but to encourage people to be engaged in action on that issue - and this is just one way to do that."

Lucy's Thursday meetings will continue and she hopes to "get a bit more student involvement".

She said she read often about the topic, taking care to use "reliable sources" because "there are lots of different things out there".

"It's a very important topic that should be talked about more often," Lucy said.

Lucy's dad, Mark Lyden, said he'd found it "extremely disappointing" that Lucy's written request to the city's principals, asking for support, had been denied by the Department of Education.

"The point needs to be made this action on the 20th requires absence from school for no longer than an hour or hour-and-a-half at the most," he said.

"The only time I ever was out of school was to smoke cigarettes.

"This is a really important issue and for there to be so much resistance ... that children who have to live with the consequences of [climate change] cannot leave school for an hour or an hour-and-a-half is, in my view, absurd."