We're in these seats SFO-LHR on a 388:

A BA agent told me that the pax in 58A can walk aft in a narrow space between 59A and the window, so they don't have to climb over my wife in 59B. Is that true?
If not, then would it be an option for me to move to 58A, so at least it'll be me climbing over my wife and not a stranger? And that would work for any window seat plus the aisle seat one back, right? Only we wouldn't be next to each other.
And is there a privacy partition between A and B?