Firstly use the full address part of the checker, postcode can be hit and miss and if Sky LLU phone number will now fail.
Also on phone number the old number at the property will now be marked as not installed, and it may be in the process of updating for the new number, so hence full address checks.
It is possible for a FTTC cabinet to fill up, but so long as still lots more properties that might connect in the area a new cabinet will probably appear in due course (time frame variable so i don't guess).
You can get shorter delays where the cabinet is not full, but they need to do some more work to the existing one to add capacity for more people, that should be fairly quick ie. in the weeks.