Brooke Smith, seven, from Caerphilly, and Hengoed’s eight-year-old Zac Ryland-Jones will compete in the category of under-12.
The duo at Shappelles dance school in Ystrad Mynach is practising together, spending four hours of training a week.
Brooke and Zac, coached by Kay and Sean Perry, have already competed together in five races, each time reaching the final.
Zac, who started dancing in February, continues in his mother’s footsteps, Bethan Ryland, who was also a Shappelles performer and Mr Perry’s training.
Brooke, who performs faster than her friend, has participated in seven events on her own.
The youthful couple is going to dance the cha-cha-cha, samba, rumba and jive together.
Coach Mr Perry said: “Brooke has been performing longer than Zac, so we thought that together they would be making a very successful pair.
“With them, we have great hopes. Both of them will be very successful as they get older.
“Blackpool is a British national championship, so dancing is going to be the best 35 British couples.
“I think a lot of couples will be 11-year-old in Brooke and Zac’s category–so much older than them.
Mr Perry added: “It’s their first time and it’s a tough competition, so we’re sending them to see how they’re going to do it and it’s going to give an idea of how they’re going to get better.
“It’ll be a very high level of competition.
“I just want them to enjoy it and then go on and maybe they’ll take it in two years, maybe three years. That’s the concept. “Brooke’s dad, Paul Smith, looks forward to seeing his daughter and dance partner compete on the world stage.
“She’s an amazing talent. It’s amazing to play at Blackpool for a seven-year-old.”
“I continue to push for next year’s world competition in Dublin.”