If the Brits were smart, they would kiss Airbus goodbye. Be the first rat off the sinking ship, not the last.
My fearless prediction: The A350XWB will never fly. It is vaporware.
The Brits should work on re-developing their own independent aerospace industry. There is a lot of money to be made on short haul/moderately sized aircraft.
Here's a plan. Boeing should buy out Airbus' operations in the UK lock, stock and barrel. They can then use the facilities to build the next generation 737.