Collocations for loo - noun

public
outside
gents', ladies', men's, women's

go to, use
Can I use your loo?

be desperate for, need
We got stuck in a traffic jam and I was desperate for the loo.

flush, flush sth down
He flushed the letter down the loo.

paper, roll

in the loo, on the loo

Loo is used before these nouns:
seat