The gross figure would add about £7billion and there are estimated another £5 billion 'additional expenses coming such as cash for the planned comical EU 'Army'
London Man: healthcare, infrastructure and deporting all the "migrants" back to the Middle East.
You will be spending two to three times that on tariffs to import anything from the remaining EU nations (IF they will even trade with you!) in "raw Pounds Sterling", but the real cost will be even higher as the Pound continues its decline against both the Euro and the US dollar….
The delicious irony is that your damp & fetid nation will be overrun by "economic tourism", ie foreigners coming there to buy stuff to take home with them because the Pound is so weak!
Are you aware that just to service the UKs national debt as of 2015(£1.56 trillion) required £43bn? If I were a citizen I would be demanding they pay down that debt, not spend it on more social programs!
Taking out the enemy of the state ie the Royal family, rothchilds and bankers
The best way to benefit society with that money is to stop government stealing it from its rightful owners in the first place.