The station for Greenland Dock is Surrey Quays, but they don't signpost it at the station in case, you know, the wrong kind of people go there. It was one of the first Docklands developments, as the low-rise and human scale (as the architects say) of the buildings shows. It was the first of the London docks to be built (as opposed to riverside wharves) (more details here) and it's pretty darn large. The Royals are larger, but some of the Isle of Dogs docks are smaller. On a sunny day, it's a pleasant place to walk around, with houseboats...
and little feature places as well.
When you get to the Thames, turn right and start walking along the Thames Path towards London Bridge. It's a nice stroll.