I have been to HK this summer. I didn't work there, but I can fill you in about the life in there.
First of all, if you are British, you should have no problem about the community. There are lots and lots of people from around the world in HK, so ethnicity is not a problem.
As you know, HK was a British land once, now it belongs to China. There are a LOTS of "mainlanders" (as called by Hongkongers, means Chinese who comes from north, Shenzhen) coming from Shenzhen (the adjacent Chinese city) everyday, the borderline is always packed with Chinese.
If you want to pass to China for any reason, if you haven't got a valid visa, you may be charged a high fine, since you are British and some Chinese really doesn't like British, for "desecrating the Chinese land for 150 years"(HK was British land for 150 years). Never forget this, HK is NOT China, even though Chinese government says otherwise. So get a valid visa, OK?
HK is an old city. Really old that is. We always saw and knew HK from those glamorous photos, but real HK is not like that. I advise not to go there with high hopes, buildings in Kowloon are very old and ugly, the city itself is cramped, every place is very narrow. Gaulong ( Kowloon ) is the part where the "poor" lives, but it is the center of the city. Hong Kong Island is the place where the rich lives.
Everything in the city is very expensive. As there is a saying goes: "You need two things to live in HK, first you have to be rich, second, you have to be incredibly rich" :)
Property prices in HK are sky high now, as it was announced that HK has the most expensive properties in the world. So if you were planning to buy, or even rent a house, good luck.
But don't let my words scare you, go to HK and live there. But my friend, I recommend you to study some Chinese or even some Cantonese before going to HK. I can speak Chinese (Putonghua-Mandarin) and some Cantonese. Old people in Hong Kong cannot speak Mandarin, but they can speak good English alright.
Have a nice day. :)