I am from Fanling so for me trying to find a Church without going all the way to the city is hard.
ShaTin area, okay - here are some links.
ShaTin Anglican (everything in English - it has been a while since I visited this Church, but it does run out of a school). There is a map on their website.
Elim Full Gospel Church (A Chinese Church, the Pastor is English and preaches in English with a translation into Cantonese. All extra Ministries are in Cantonese. The Church is not far from City One station in ShaTin. (I assume you're not going to isolate your Children from the local community, also if you attend only on Sundays you can sit through the service quite easily).
Tai Po Baptist - I can't seem to find the link but they have a separate English fellowship in the Tai Po area.
Kowloon International Baptist Church (KIBC) (English speaking Church - have many Ministries for English speakers as well as for International students from mainland China, and Western Countries. I am quite excited to share the Gospel with the mainland students - they come because the service
is in English. There are Ministries for parents etc. I am attending and praying about joining this Church. KIBC is in Kowloon Tong near the Baptist University.
Also, because KIBC receives many International students you will more then likely meet others from Chinese U. My wife is a student there also.
Home School - not sure, but I do know you can put your Children in the local school system, it is free for 9 years, and heading towards 12 years for free! The work load will be more then what you are familiar with in your home Country, you wont be able to help them learn language, but they will be bi or tri-lingual. I am a newly wed, but my wife is a local Hong Kong Chinese, so maybe my thoughts are different. I do hope the Church lists are helpful. God bless - yours in Christ - Dean