Living in Sai Kung gives you access to Kau Sai Chau which is a very high quality public course but you need to have a ahndicap to play and book in advance.
The other course such as Fanling, Clearwater Bay and Deepwater Bay are very exclusive but can be played with members I presume.
The best option is to hop over the border and play- you get a really wide range of choices from Mission Hills at the top to some older links courses at the bottom. Weekdays are the best to play as they are both quieter and cheaper but some of the older courses in China can be fairly quiet. ironically the newr courses are often booked well in advance and are pricey but the older, more established course are more available and cheaper. You can do a day trip taking the ferry to Shekhou, a taxi to the course, green fees, buggy and jacuzzi afterwards for about 1,000-1,200 HKD each if there are 4 of you. That's on a pretty decent course during the week.
You can check out ??????007: China Golf, Hong Kong And Asia Golf Course Guide, Golf Vacation for morecourses and packages.