Something you might not know about is Do Not Adjust Your Set, one of the many training grounds for the future Pythons, like The Frost Report and At Last the 1948 Show (source of the original Four Yorkshiremen sketch). DNAYS featured Michael Palin and Terry Jones (who had also worked on The Complete and Utter History of Britain) as well as Eric Idle. This was a kids show, which is kind of stunning (although if you look at a lot of the mad kids show at the time, perhaps not quite so odd) so a lot of the humour is very nonsensical in the Goons/Spike Milligan/NOBA vein of absurdity. You can really see the connections between the Pythons and what came before them.
Of course one of the key reasons to see DNAYS is the Bonzo Dog Band. Why anyone thought they were safe for children, I don't know. The ginger geezer Vivian Stanshall and the delightfully daffy Neil Innes headed a rotating roster of musicians but those two were really the magnets. I've gone on at length about both of them, so if you don't know them yet, you should stop reading right now and just go look at the videos widely available at a certain tubish site.
A fave moment, appropriate for the season: the Bonzos sing "Monster Mash" for your delight.
As usual, find the whole roundup of overlooked a/v over at Sweet Freedom.