I have some flat rate envelopes & boxes to ship & was going to Click-N-Ship but my printer is out of business momentarily. Can I bring them here to pay & have postage/shipping labels printed/applied by staff?

I'm not referring to address labels which I can write directly on the packaging. I'm referring to postage (like stamps) that verify that I've paid for a specific service (flat rate shipping in this case). With Click-N-Ship it's printed with the address all one label. Unless I'm mistaken?

No they have peel and stick .you must hand write..