Per the above, no.

The UK purchased right of first refusal on the first 100million doses of Oxford/AZ produced in the UK factories that they funded.

The EU also funded factories (in the EU) but did not purchase right of first refusal only best efforts contracts.

The USA has a full ban on exports till they are ready to export.

There is no UK prohibition on exports.

The UK is not blocking exports. The EU were free to conclude contracts with the (not very productive) UK manufacturers at the same time HM government was doing so.

I’m aware of the US blocking exports of certain things but as far as I know the UK isn’t. If you have evidence proving otherwise I’d love to see.