Our GP practice has just shared the letter from the NHS detailing how vaccine capacity should be increased to hit the January government target. It's dated Friday 3 and says the NHS website will be changed from Monday 13 to offer boosters after 3 months and in age group cohorts. In the meantime the 6 month gap will apply.
Capacity increases rely on jabs from:
The military
St John's ambulance
Medical students
Non medical people previously trained up being asked to help
Current vaccinators working more shifts
Hope this helps explain things to anyone currently frustrated that they can't get their booster even though Boris announced it week ago.