They will face Leinster in the final at Aviva Stadium in Dublin on May 20 after they qualified by beating English club Exeter 47-28, with Kerr-Barlow among the try-scoring action.
As defending champions, Kerr-Barlow told French rugby newspaper Midi Olympique it had been tough for the Ronan O'Gara-coached side this season. Still, they accepted there were several fine teams in the competition, and they concentrated on their own efforts.
Winning last season was one of his career highlights, along with being a member of the All Blacks' World Cup-winning side in 2015.
"Seen from the southern hemisphere, we don't realise how hard it is to win the European Cup. This event brings together all the best teams from the countries of the Six Nations and even more now. Just getting to the final stages is already a challenge in itself."
Kerr-Barlow said while it was natural when younger to be obsessed with the quest for trophies, time has shown him that his main reason for playing was to create great memories for his friends and family.
"If the environment is good, if everyone is focused on excellence, the titles will eventually arrive. And that's what we'll leave in the heritage for all the kids in La Rochelle.
"The cohesion within the dressing room, and the link between a team and its coaches, can make it possible to accomplish great things. This is the case in La Rochelle and that's why I feel privileged to play for this club."
He said that while winning the Rugby World Cup had been a childhood dream, and it had been great to be part of such an All Blacks team, he admitted that he had an equally good memory from one of his victories at Hamilton Boys' High School.
"With my friends we beat guys who were much stronger than us and favoured to win. But we ended up winning. There were no cameras or titles, but it was with my childhood friends, the ones with whom I knew everything from 14-18 years old. It may seem small, but it has great value for me."
It had been tough to leave the All Blacks system and move his family to the other side of the world to a non-English-speaking country.
"It's been a radical change. That's not negative, but it's different. We had to go through those hard times to start with but we are enjoying it now."
Being part of a side that has grown so spectacularly was enjoyable.
"When I arrived, Gregory Alldritt was regarded as something of a hope for the future, and now he is probably the best No8 in the world."
As a result of being born in Australia, he has been touted as a prospective Wallaby at this year's World Cup but has not heard anything.
"I would love to play for Australia. It would be an honour to wear the colours of the country where I was born. I am available, but I understand that their staff has their usual players to rely on, and while I would be happy to be there, it is unlikely.
Comparing how halfbacks operate in New Zealand and France, he said that halfbacks were asked to be more smugglers and more dynamic in New Zealand, whereas, in France, he could prowl around rucks and hang out behind the big forwards.
"There is more footwork in the Top 14. This is the aspect of the game where I have had to do the most work since arriving here. You have so many classy halfbacks in France I had to adapt my play to compete.
"The Top 14 is more physical. It's slower and more centred around conquering the opposition than I have been used to.
"I think I am a more balanced player since being in France. At 32, I have also gained a lot more experience. If I could go back in time and bring all that I know now as a younger player, I would have been a much better player."
When finished playing Kerr-Barlow said he would like to get involved in coaching, but he said that would be a family decision, and they had yet to talk about that, and he hadn't been doing any coaching courses.