Morning Darren
Living in the land of 20mph speed limits certainly isnt going to help, to get the Soot burned off even though you have triggered it with Carly will need a bit of Help. Engine revs need to be at around 3000rpm Engine needs all Glow Plugs working as they are used to achieve high combustion temperatures, if 1 is not working the Regen Cycle may not work.
Hope this helps
Dave