Again, this is simply not true. Yes, the UK signed one particular contract on Aug 28, so one day after the EU with AZ. However, the UK had a binding contract with AZ since May.
"However, the key lies in an earlier agreement that AstraZeneca made back in May with the U.K., which was a binding deal establishing “the development of a dedicated supply chain for the U.K.,” an AstraZeneca spokesperson said."