So it sounds like as people move out that ports just get left on FTTC ready for the next person then rather than being 'decommissioned'?
Quite the opposite, a cease order will be raised for the day the service ends, an engineer will attend at the cabinet and remove the fibre ties, reconnecting the line after, the next punter may have ADSL, and if not disconnected, this would stop that working.
I dont suppose that when i arranged the move a port would have been reserved for me would it? or is that just wishful thinking?
Well if you've ordered it for the new address, then a port will be reserved at some point between then and now.
Capacity issues are often resolved by the 'simple' addition of an extra card in the FTTC DSLAM cabinet, this then makes more ties available.