The answer is that early on the English were looking for a "Northwest Passage". This would be a shorter trade route to East Asia. For a long time it was believed that there was a large body of water in North America that would lead to the Orient. The English were interested in the raw materials that they could find in North America, including the islands of the Caribbean.
One reason for English exploration was, that the English wanted more land. Another reason was, that the English thought there was a large body of water in North America, that made a shorter trade route to East Asia.
