You should get the ticket (Economy) for about 50% less by travelling ex-London/UK. Any good agent should not need anything like a day (for a standard RTW) - better to check a company such as Trailfinders - they know their stuff and could provide you with a good price/schedules in a few minutes on the phone. e-mails agencies hate as there is a lot of work that goes into pricing RTW routes and they just assume that you are emailing lots of agencies/airlines and are therefore a waste of time. Just my experience.