聖母無玷聖心幼稚園

You can check this out directly with the school. I think this school may hire teachers with British accent.

General speaking, native teachers come and go, they won't stick to one school for very long time, meaning, the native teacher you meet this year may go back home and you will meet another one in next teaching year.

Most "native teachers" hired by HK registered schools hold the British qualification of "Teaching English as a Second Language", native speakers from UK related countries may obtain this qualification (England, Canada, Australia), and they defined "native speaker" as they were born and brought up to use English as the first language, not the race, so it does not matter even some teachers bare a non-white look.

Different accents between British and American should be fine to the kid, they cope with it very easily, don't worry (but watch out if your domestic helper speaks heavy the Philippines accent).