First of all, it's not just a travel agent. The Continental Shop is worth a visit for anyone pining for a little slice of jolly olde England. The front of the store is a mecca for British expatriates looking for their brand of marmite or videos of TV shows that even PBS won't air. It's fun to browse through their magazines, see their extensive tea collection, and maybe pick up a t-shirt with the Underground logo.
In the back of this cluttered shop is a cluttered office that serves as the Continental Shop Travel Agency. They are very friendly people who are extremely familiar with all the ways to get to Europe. They can hook you up with package tours, give you some advice about places to go, and do it all with a bit of English charm.