They don't have to wait for UK approval to apply to the US and or EU. They can submit anytime. This is NWBO and they are not capable of applying to more than one regulatory agency simultaneously. And the ADCOM is decided at the FDA level. The FDA chooses whether or not to have advisory committee.
But that is the point Zadie. Without the manufacturing validation of the EDEN system they will not have adequate production to satisfy the demands in the USA or EU whereas they can meet the demand in the UK with the manual vaccine manufacturing system.
Once they validate the EDEN system, no problem, they can and should submit an MAA to any jurisdiction where they can meet the demand.