If you prefer a British accent, then you need to imitate one.
When you practice listening, you should listen to a variety of accents, but you can focus on British accents.
The most important thing, though, is to spend some time each day *imitating* a British accent. Try repeating after a set of pronunciation tapes for ten minutes each day.
Have fun!
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http://blog.sina.com.cn/m/john/