Simon Cowell -- 'I'm Gonna Be a Good Dad'

Simon Cowell tells TMZ ... he knows he's going to be a "good dad" -- but there's just one problem, SC admits he's clueless when it comes to shopping for a kid.

Simon hit up Planet Dailies LA at The Grove yesterday in his massive Rolls-Royce -- when he told us he's "excited" about his baby with girlfriend Lauren Silverman ... saying, "I'm gonna be a good father."

But when we asked if he planned to pick up a few items for his fetus, the 53-year-old replied, ... "No. I don't know how to baby shop."