It may have changed since my time but there was a provision for you to repeat some lessons at certain stages of the course, but that could well have been done away with.
As for the examiners, in NZ all examiners are in house. In Bournemouth for CPL/IR they are based at the airfield, not far from CTC and aren't exclusively CTC examiners but there was never any long waits for a skills test. Again that was a while back.