Flashing Emissions Control Light > EPC Light > breakdown!!

Hi all,

I was driving my 2014 Octy 1.2 petrol yesterday and the emissions control light started flashing for about 10 seconds, then the EPC light came on.  Then I lost some acceleration and gradually got slower until I pull in off the motorway at the next junction.  By the time it was safe to stop there was a sort of chemical smell in the car and there was some blue smoke coming out the rear.  Once I turned the engine off it won't restart.  Oil and coolant levels seem ok and the engine didn't overheat.  The only symptom before hand was that a few days ago the car momentarily felt a tiny bit juddery like the engine was mis-firing, but only lasted a few seconds.  Any idea what this might be and what it might cost to repair? 😭.