The CAA library used to have May & Nov ABC guides - I spent a day there looking at at Pan Am's transtantic scheules from the start of the jet age until its demise. I don't know if it is still open - it would be worth giving them a ring.
The British Library has most versions although you have to order each issue you want at least 48 hours in advance & they truck it down from Boston Spa. In fact I was looking at the June 1977 ABC for some research I was doing today. You have to go to the reading rooms at Kings X or Boston Spa.
Their website is
Explore the British Library (bl.uk)
Just type in ABC world airways guide & select holdings. Alternatively give them a ring on 01937 546060.