Congrats Tim! I know you have been working on this for a long while!
Very cool. I always thought it was interesting that these Alan Cass books were coming out at the same time Marvel was selling pence copies in the U.K., and also that Cass seemed to reprint everything except DC; from Atlas/Marvel to Archie Adventure/Mighty Comics to Charlton to ACG. Throw in the L. Miller & Sons books, Mystic and Spellbound from the same era and the history of Marvel in the U.K. gets confusing.
About when would these have been on the stands, 1965?
I'm not really sure, for whatever reason Alan Class didn't have a publication date printed anywhere that I could find. If I had to guess I'd put them in the range anywhere from 1962-1965 though.
I do know that I worked on this run for about three years, in that time I saw at least two Pence copies of every FF from 1-6 for sale but not other copies of these. I have no idea what the print runs were like but they don't seem to be very plentiful.