The most important thing in spoken English is the language environment. As far as I know, it is better to cultivate oral English ability in non-test areas in China than in Wall Street and EF, because it can provide an all-English environment. But the cost is also expensive, and you are going abroad soon, so the time should be too late.

As for adaptation, because I studied under the British education system, there is no problem in this respect, so I don't know much about the adaptation problems that China students need to face after going abroad. But I think in daily life, the English level is not the biggest influence on adaptation, because most communication is not language, but non-verbal communication such as body language.

If conditions permit, it is much better to chat with a foreign friend than to attend English training. Because most English training focuses on teaching you IELTS and TOEFL, rather than really teaching you the language ability to adapt to foreign life.