You DO need a valid passport to join any of our trips. Many countries require that your passport is valid for up to 6 months beyond your date of arrival into the country so make sure to check your passport expiry date with plenty of time before the trip just in case you need to get a renewal before departure. The United Kingdom does have Electronic Travel Authorization (ETA) requirement for all non-British travelers entering the country. Please visit for details: https://www.gov.uk/eta