To be fair, they are anticipating problems. Look at ventilator cases, on 18 Sept, there were 138 ventilated patients across the UK. Today there were 975, nearly a 7 fold increase.
It would be abject neglect by a government if they waited until the beds were full before taking action.
I very much doubt that your friend was told categorically that 4th Nov would see the start of national lockdown. The stats at that time whilst increasing didn't suggest the country needed a full lockdown hence all the local restrictions. It may well be there were several models looked at and...