Hi Mark – welcome to the unwelcome world of copy rights for sheet music. You won’t find many people openly displaying sheet music on forums due to copyright issues.
The best thing to do is search on the internet and see if anyone has displayed it. I buy all my sheets as this keeps people like JF in income.
But i think there are older songs, where the copyright has expired and these are free to the public.
Joy to the world is a simple song, you could have a go at guesing what notes come next and writing them down – this is a good exercise to do when starting out, as if you leave it to do years later – in terms of improvising it gets harder to do, so i would start now