I think you would have to have full cream milk to make butter and it takes a while for it to happen anyway, can't you 'nip' somewhere and get a pack or have marg ..yuk... If you are pushed?
Since butter is made by churning cream I don't think you have any chance. When I was a boy I took the cream off the milk (not homogenised in those days) and made butter from it. Since milk is homogenised nowadays you can't take off the cream and, in any case, being semi-skimmed milk, there's not much cream in it, you're fighting a losing battle.
What is it that you want the butter for? Olive oil often makes a good substitute (e.g. when cooking certain dishes or on nice, crusty bread when served with a savoury dish) but clearly not for everything.