Alternatively you could also consider letting your children grow up in the UK. If your plan is to have them continue their education in the UK anyway, you might as well save yourself the hassle of relocating them to Hongkong only to relocate them back to UK later.
How long are you planning to stay in Hong Kong? If not for too long, why not consider putting them in local schools to learn more Chinese? Otherwise, like many ppl I know, they may end up not being able to read Chinese.