It is tough. But she feels it gives her a chance to get the best of both worlds - an excellent education and expert swimming coaching.
We went back to Kenya with Achieng on what will be her last holiday before 2012. From here on in, the combination of the Olympics and A-levels will dominate, so it was precious time with her mother and family.
Achieng Ajulu-Bushell (R) returns to Kenya to visit her mother Helen Bushell
"I don't see my family all that much and when I do it's important to spend time bonding again - enjoying our time together," says Achieng as we joined her on a family safari.
Watching her spotting rhino and zebra with her younger sisters, it was clear this particular Olympic dream has had a real impact on family life.
This time together is rare and precious. They are all used to the separation and the goodbyes, but it is still a strain.
"Being able to just come home, be herself, be with her family is very important," said Helen Bushell, Achieng's mother. "Her sisters are effectively growing up without her, there is very little contact really. It's such special time when we have the family all together."
The teenager's week back in Kenya was also an escape from the pressures of her life in the UK. In London she has early morning training and late nights catching up with homework.
For her family, protecting Achieng from burn-out is a priority and her time in Kenya is vital to that. It is a chance to stop and to rest.
Achieng Ajulu-Bushell (centre front) with swimmers from the Aqua Kenya Swimming Club, which Helen Bushell founded
Achieng's potential was spotted early. One of her first school reports predicted that the six-year-old Achieng would be a "swimming star of the future".
As a young swimmer she swam for Kenya but she has now made the difficult decision to switch sporting nationality. As a holder of a British passport, she will now swim for Team GB.
"Obviously it was a difficult decision but you can only hold one sporting nationality. I was born in England, have a British passport and it's where my Mum is from... the support, the facilities you get is so far ahead, so in terms of that it's a no-brainer," Achieng explains.
Ahead of meeting Achieng, I had my own thoughts as to what she might be like. Ferociously driven, obsessed by swimming, single-minded?
I found somebody quite different. She is without doubt fiercely ambitious and desperate to compete in London 2012.
But unlike many other young athletes, swimming is not everything to her. She is brutally honest about where it fits into her busy life.
"Swimming is one of my main priorities. It's such a sacrifice - everyone knows how much you've got to give up. There's swimming, there's family, there's school, there's friends so obviously I have a lot of other stuff I need to fit in," she says.
But do not dare doubt her desire to win. When I questioned whether her busy life meant she lacked that competitive edge, she nearly bit my head off.
This is a young woman trying to strike the right balance between being a normal teenager and an aspiring Olympian. Nevertheless, she feels she is getting it just right.
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