I used to work for Pharmacia, a company which merged with Pfizer so know the Puurs facility well.
Pfizer believe they will have a good handle on the vaccine's effectiveness by the end of October and will seek a rapid review with the US FDA to get the drug licensed for use there.
For UK the licensing authority is currently within the EU,( they approve medicines for all EU members) although likely to be the UK MHRA after Brexit. Hope this possible change won't delay the approval of the vaccine for use in UK