I doubt there would be any net loss of jobs over a reasonable period of time.
I can say, without fear of reprisal, that your suggestion is utter nonsense.
Why can I say it without fear of reprisal?
Because your comment is in no way linked, connected to, or makes reference to the possible trade agreement conditions.
It's so obvious:
continued free trade = no affect on trade
Some sort of bilateral agreement will take years = many years of uncertainty = decrease in UK GDP, devaluation of GBP, potential loss of jobs, potential reduction in living standards, etc.
Reliance on WTO regulations = (as well as years of uncertainty) decrease in UK GDP, devaluation of GBP, potential loss of jobs, potential reduction in living standards, etc etc etc.
Your projection is based wholly, but not stated by you, on continued free trade. Whereas my projections are entirly connected and determined by the trade agreement conditions, if any.
That's why I can say your projection is utter nonsense.