Watch Fawlty Towers again to be reminded of what hotel service is like when Brits are in charge.
And replace Manuel with VIcky from Little Britain.
In practice, there will probably be temporary visa schemes so that the stereotypical farm worker, NHS nurse, hotel cleaner, etc. can still come to the UK to work. If not, hotels will probably have to pay more in order to retain their staff - instead of relying on a revolving door of "here to learn English" Europeans - which might eventually feed into higher room rates.