Prince Harry found a meaningful parenting moment in a relatable Monday morning with his kids.

During his annual appearance at the WellChild Awards in London on Monday, Sept. 21, which celebrates seriously ill children and those who care for them, the Duke of Sussex, 42, opened up about breakfast that morning with Prince Archie, 7, and Princess Lilibet, 5, as the family settles into its new routine in the U.K.

“At breakfast this morning, they had a bit of Monday blues,” he told HELLO! Magazine. “It was always Sunday night blues when you’re being sent away to boarding school like I was, but for them, at breakfast this morning, I decided, you know what? You’re just being a little bit tricky, so I’m going to tell you exactly what I’m doing tonight.”

The morning mood gave Harry an opportunity to turn the moment into a meaningful conversation, telling Archie and Lilibet about the children and families he would be meeting later that day.

“They were genuinely fascinated and asking all sorts of questions,” he said. “So, like with all of my work and their mum’s work as well, whatever we can do to try to instil some of that awareness, I think is absolutely crucial.”

The WellChild Awards “celebrate the inspirational achievements of seriously ill children and those who care for them.” Harry has attended 15 of the annual ceremonies since becoming a patron of the organization in 2007, and he said becoming a father himself has changed the way he experiences meeting the children and families involved.

“Once you become a parent, it does change everything,” Harry said. “It’s not the fact that for all the years that I wasn’t a parent that meeting the kids didn’t matter as much, but you suddenly realise how grateful you are to have kids that aren’t sick.”

“And again, day in, day out, coming off the back of kids being out [of school] for 11 weeks… but you find yourself going, ‘Wow, in that room with those parents, you really can’t complain about anything,’” he continued. “Of course, it’s all relative, but the inspiration that I get from these guys – not just the kids, but the parents themselves – it fills me up for a whole year.”

Harry, Meghan Markle, and their children arrived in England on Aug. 26, in time for Archie and Lili to begin their fall term at their new U.K. school alongside their classmates. However, just two days into the term, the Sussex children switched schools due to security and logistical concerns regarding their commute.

A spokesperson for the Duke and Duchess of Sussex told PEOPLE at the time, “The decision for the children to move schools was taken following a discussion with the family’s security team about the practicalities of their current arrangements.”

Getting Prince Archie and Princess Lilibet settled in “has been, and remains, their focus. Everything else will fall into place when the time is right,” a source close to Harry and Meghan recently told PEOPLE.

Harry also shared a lighthearted anecdote about his children’s adjustment to life in the U.K., revealing which popular British food they’ve become fond of.

“[Beans on toast] hadn’t gone down very well,” he admitted, but said Archie and Lili had taken to Marmite on crumpets. “Is that a British thing? Because it’s always been in my life, and now the kids are eating Marmite on crumpets, which is big for me.”

“They do [approve], they do very much. I mean, they used to diss me for having Marmite in the house, and now they’re in the UK it’s like that’s kind of like water under the bridge, so it’s good.”

The appearance was Harry’s third charity event in less than a week; he has flown solo at all the outings as Meghan remains home with the kids; insiders say her focus has been on getting Archie and Lili settled amid the whirlwind move from California to the U.K.