However, history shows that after the initial set back, we tend to get our act together.
Well, yes, but getting our act together didn't bring back those killed and injured in the appalling carnage of the Somme and other battles. (It is a digression here, but clearing out my parents' house, I found a report my grandfather had written about one of the Somme battles, which I have kept, and which makes for harrowing reading. He survived WW1 but barely talked about it until the end of his life when he tried to impress upon me and my brother the horror of it all.)
Ditto the appeasement of WW2 - this did not bring back the millions killed, never mind the suffering caused to the injured or displaced.
Yes, Blair was stupid and completely underestimated how many Eastern Europeans would want to come. However, apart from selected areas, where local relief could/should be given immigration is not a problem, but enough hatred has been whipped up against immigrants to cause people to vote against it. With the end result that people in places like Cornwall, who have done very nicely out of the EU, voted Leave. Cornwall County Council asked in the few days after the vote if the EU funding they had received would be made good and got the short answer no.
The solution should be a FTA that looks very close to a single market with middle grounds on other issues. If Brexit at all cost isn't sensible, neither is EU all or nothing approach.
We had opted out of the 'all or nothing' approach like the Euro, Schengen etc. We had a good deal and we (the Tory right wing) were just too stupid to shut up about it. Cameron was too stupid also.
Maybe a a FTA would work. Who knows? So far, not a word of sense has come out of the mouths of Fox, Johnson and Davis. And as for, 'speaking as a mother' Leasdom, she's now very, very quiet. So far the noise is being made by the 'Hard Brexit' camp, who won't give a damn if the country goes to rack and ruin, because they are wealthy and will be OK.