My mom holds an United Kingdom (BNO) passport (which is for British Nationals Overseas, my mom is from Hong Kong). She currently resides in the U.S. She is planning to go on a cruise to the Caribbean in February, but her passport expires in April. She will be applying for US citizenship in October, so she does not want to spend the money to renew her UK passport. Can she still travel out of the country with her passport expiring in 2 months? Also, does she need a visa to travel to the Caribbean?