ESF's web site is here:
www.esf.edu.hk
They teach the UK National Curriculum although some are converting to the International Baccalaureate Diploma (which is for 16+ only). Whether they are 'compatible' depending on many factors such as how long you intend to stay 'cause there are pupils going to North America for Universities for sure.
In your case, 7th grade and 4th grade in the US are equivlant to year 8 and year 5 in the UK system.
Other schools I know of that teach the US systems are the International Christian School, the American International School, and the Christain Alliance International School and the Phoenix School (the latter two are of Candian system, not sure how similar it is to the US system).
Hope all these help. BTW, they are all very full so it is often not a matter of choosing the right school but rather getting in a school, particularly in the middle of a school year.