The UK go it alone?
The only reason that the money the UK spent on Galileo was productive was that it was someone in Europe controlling the project.
Can you imagine the fun and games of the UK doing it by themselves?
I'm guessing that whilst the UK built the satellites, and these are top notch, the process of getting them into space will be a solid cast iron "Britannia Chariot" powered by a solid state burner fuelled by old EU passports.
Or more likely, a £20 billion project that takes 15 years and then is canned