Playing guitar to a pub?

So I recently made friends with a landlady of a pub who quickly
discovered I was a guitarist. She offered me a free spot on weekends
where I could come down and play songs to the pub, which I promtly
took up; but then wondered .. WTF do I play? So basically .. How do I
play guitar to a pub audience? Any advice would be a massive help :)

Btw, I'm 16 if it matters