China was not interested in European goods and only wanted to get paid in 'hard currency' for its own goods and commodities (China, silk, tea, etc).

The Spanish went with it but the English did not want to and decided to find something the Chinese would want. And they found opium, which they could conveniently produce in their Asia colonies. They also started producing tea in their own colonies to avoid having to buy it from China (this is the reason why India produces tea and Indians drink chai).