Trading petrol to diesel

[JamesC27]

Hello any thoughts please, currently running 57 plate clubman cooper 1.6 petrol (54000). Great second car, work mileage has recently changed and thinking about a change to the black stuff. Have seen a lovely 12 plate Mini Cooper D London 2012 edition, booked a test drive for next week. It's a second car so the size is fine, the mini's just seem a nice place to be, have looked at the fiesta ST but it doesn't work fuel insurance wise. Has anyone else made this jump?

Cheers