The BBC archives have made access to their catalogue available here - BBC INFAX - It should be noted that this is a prototype database and will no doubt be upgraded as time goes on.
This only gives listings of programmes in the archives and there is no facility to view any of the programmes listed - basically if it's not on DVD or Video then it's not available.
There is quite a bit of detail about each programme but as has been said above - an awful lot of stuff has been wiped. Much of what remains from the 60's was transferred from 2" 405/625 video tape to 16mm b/w film for sale to foreign countries. After a repeat showing in this country (UK) the tape would probably have been wiped for reuse as the acting unions would not allow more than one repeat of a programme without further negotiations regarding fees. This is a subject that is dealt with on other websites but we have lost many folk programmes such as "Ballad of the Northwest" from 1973-75 which dealt with the historical aspect of Northwest England life in song.

Cheers
Mark