You're right . . . . the distance between the English coast and the Pas-des-Calais is not going to change, and there's rumour that we won't be filling the Channel Tunnel with quick drying concrete.
Most sensible people in the UK are keen to keep the win-win situations that exist between the UK and other members states of the EU - what we want to leave behind are the undemocratic appointments of member state commissioners (who draft EU reglations and directives), the incompentence and mismanagement of financial contributions and the abuse of worthy concepts such as the free movement of people or common agricultural policy - apparently, if you own six olive trees, you can compliment them with a goat and three chickens then claim a CAP grant as a working farmer . . .
Most sensible people n the UK are OK with the concept of the free movement of people for the purpose of taking up employment in other member states, but the clue's in the qualifier " . . . for the purpose of taking up employment
". What the public concern has been around immigration has been the vast numbers who have come to the UK from the EU who have little prospect of securing employment and no means of supporting themselves or their families while they're here. At a fairly recent count, the number of EU citizens currently in the UK was estimated in excess of 3m, or around 8% of the adult working age population - a hefty proportion. It's never been made public what percentage of these people actually support themselves through having taken up mainstream employment - which should be a fairly simple exercise of looking at the tax and national insurance records, although I suspect the reason is that this would be a very politically sensitive issue.
I've used the term "sensible people" twice in this post, as I'll be the first to concede that there are an awful lot of people in the UK who are not sensible, and will have voted both ways on the grounds of silly, illogical, nonsense, prejudiced and/or bigoted beliefs. Perhaps I'm one of them . . . . ?
No prizes for guesssing which way I voted.