It is not doing well. It's turning back into the sick man of Europe. Productivity growth is among the lowest in the EU.
It bothers me immensely how quickly the truth gets discarded the moment it conflicts with EU ideology. The UK has shown excellent economics relative to the rest of Europe since the vote despite its people being told "uncertainty" would trigger a massive recession and employment bloodbath. Yet here you are, saying it's turning into the sick man of Europe!
Important big money already migrated to Ireland (mostly), but it takes some time (years, multiple) to take an effect if any.