When I first entered Anor Londo, I didn't have the Peculiar Doll. After being stuck on Smough and Ornstein with no humanity--5 Estus Flasks and unable to summon--I decided to backtrack. I went to the Depths and farmed humanity, picked up the Peculiar Doll, and defeated the Stray Demon. Now that I'm, finally, back to Anor Londo I'm eager to take on S&O, but I just want to make sure I will still have access to Painted World after defeating S&O.

TLDR: Can I access Painted World after defeating S&O?

Pretty sure you can do Painted World at any time as long as you have the doll. It's also a good place to farm souls and get the best hat.

The painted world can be accessed whenever you want, and it's got a couple of decent things to loot in there. It's also a good place to farm souvenirs for the Darkmoon covenant. Bring a bunch of blooming purple moss clumps if toxic annoys you, though.