Are there any passenger aircraft with no cabin access to/from the cockpit?
The only one I can think of is the Junkers F13. It has an open cockpit and an enclosed 6 passenger cabin. There's no access between the two areas; only a small window.  


Credit:THOMAS LÜTHI / RIMOWA 2016

The CEO of Remowa is having recreations made of the aircraft which first flew in 1919. It was (according to Rimowa) the world’s first all-metal commercial aircraft.