Ok, update. Took the car to diagnostic specialist. He erased all faults codes and I ran the car for 15 minutes or so and the dpf light didn't return.
also ran a forced regen on the dpf and hopefully all will be well.
Regarding the mot pass with the dpf I asked about how they removed it etc and they said it shouldn't be a problem for mot. They also explained how common the problem is and that they have had numerous mazdas in looking the dpf removed.