Car appreciation... the aesthetics, the engineering, etc

does one actually gain that much for the extra £££ spent at a dealer?

No, but buying privately can be a painful and time consuming process. There are a lot of cars out there which are not worth viewing, but often you only find that out after wasting time travelling to view.

If budget allows, I would suggest a car supermarket. They have their own hazards, but you get to see a large number of cars in one location, and as they are nearly all ex fleet, they have generally been maintained to an acceptable standard.