Been left foot breaking the second you just tap pedal it kills the TC instantly but light remains for a couple of seconds
It is not unusual for the TC light to stay on for 1 or 2 seconds after TC deactivation. Sometimes it's hard to say for sure when you'er not doing the testing yourself but from what you say, I'm confident that the SLABS ECU is working as it should, i.e. break pedal down and TC off.
At this stage, I would check the brakes and make sure they're not binding and slowing a wheel down.