We bought ticket to go to Churchill War Room and City Cruise with a combo discount. The whole process is very fast and convenient. You will need a printer to print out the ticket. We use the hotel lounge for printing and it is convenient too. You can select different dates for the two events, which is convenient. The official site for Churchill War Room needs a specific entry time, while our ticket does not need. Only the date needs to be pre-fixed. This is an advantage of booking tickets here. City Cruise had a long line, but it's a good value to have a ticket to be able to hop on and hop off for the whole day. We went to Greenwich and it was a relaxing trip. The combo discount has good value.