I really really wish I shared your optimism.
Our economy will flourish.
No problem at all with the Irish border.
Foreigners will not be welcome...unless they are super skilled.
We will do our own security.
No problem with items such as medical supplies.
We don't need farmers anyway. So 40% tariffs on sheep and even more on dairy doesn't matter, does it?
We can import what the hell we like - even if the quality and safety standards are no as good as currently (foodstuffs etc)
The EU will go bankrupt.
British courts will rule on British laws. (Oh, hang on...)
We don't need reciprocal free medical care when abroad, do we, we can buy medical insurance.
Hooray! we will have to get one of those funky green card thingys and wait for customs checks when entering/leaving Europe.
We can compete against the EU instead of collaborating with it.
The collaboration between our various science projects is overrated.
We will get our blue passport back.
We wall be poorer, but I'll have a warm smug feeling in side once we leave.
Our kids will be deprived of travel/working/living in Europe to a large extent but why on earth do they want to leave Britain in the first place?
If the foreigners get nasty with the trade deals then we'll show 'em what the Bulldog spirit is all about. We lived through the Blitz don't you know?
We will be able to buy bananas as bent as we wish.
What's not to like? Have I missed anything?