Ok, £4 Billion it is then...
Half a billion to charities as well with about a quarter of that amount going towards scientific research into genetic's and space technology.
Half a billion to be divided between my family and closest friends
1 billion for kept in the bank for investment in the market
2 billion to spend on myself.
I would spend them 2 billion pounds on
-My own custom made luxury castle. I would probably build it in a rural area in England, but in convient acesses of a nearby city. It would come with a racing course, a selection of racing car's including but not only, the Porche 911, Bugatti Veyron and the Ford GT. I would also buy an offroad course and buy a T-34, Sherman Tank, Leopard tank, and a Centurion. A shooting range where i would have a wide collection of guns. (Lee-Enfield rifle, Moslin-Nagant, M16, AK 47, Barrat .50, mp40, Thompson sub-machine gun, MG42 and Bren machine gun)
I would probably spend most of my time writing novel's, travelling around the world, and messing about on my estate.