The UK will perhaps be able to establish a fringe activity with some admirers watching from outside (spectator sport is a pastime). The question will remain whether the UK will provide an internal environment, with or without external co-operation (we will not know for some time how long the UK will be drifting on its floe seeking "great new opportunities and deals" before any emerge as useful and productive), one that raises it from its current mediocre standing in international comparisons of social criteria (birth survival, health care, education, life expectancy, gender/other socio-economic equality, etc., etc.) - look at the lists available (although not generally in the UK press which lands the UK at No.40 in its usefulness).
The point of the negotiations is that the UK is asking for a deal, concessions, with/from an organisation which it is leaving. To suggest that it is in a position to bring about its wishes by sending someone different to dictate is a somewhat curious notion.
Personally, although it is currently astonishingly tolerant (sometimes even proud) of living what elsewhere are considered rather backward lives, my assessment of today's UK population is that it will not long celebrate being consigned to the status quo, far less a perceptible deterioration in living standards and survival, as may happen. Maybe I am wrong, maybe the UK's people will continue to be champion moaners and soldiering on - maybe it is an improvement of sorts to go "backward", thus having even more stuff to moan about.