I imagine that the lack of keycode is Fiat-wide.. i.e. that all UK dealers retained these for safety reasons. Should I be able to get this info at any Fiat dealer?

And what sort of cost is a new non-plip replacement ignition key?

I did a bit of a thred on this key coding business. Have a look here. https://www.fiatforum.com/multipla/179564-key-coding.html

perfect, thanks