Since that first reading I've always checked secondhand book shops just in case they have any Catton on the shelves but I've not had any luck so far. I imagine it would be a bit different if you were shopping in the US, however!
Anyway, by roundabout means, I came across the website of a secondhand book store in Wellington called Haven Books which had a copy of the Army of the Potomac trilogy. I ordered it and it arrived today, well-thumbed, yellowed, and obviously much-read. Just how a book should be.
But my search also turned up another gem - a C-Span video of a lecture on Bruce Catton given at Gettysburg by David Blight. I won't spoil it with an inadequate introduction, but if you have an hour and fifteen minutes to spare, you might find it worth your time.
To close, the Gettysburg movie, Catton, Foote, and Burns have no doubt been the catalysts for many a Civil War obsession. Do readers have any other particular books, videos or lectures that got them interested in the ACW?