Not so.
The independence only works when it comes to shelling out. No doubt, eventually, the EU will also pledge a wheelbarrow full of cash (confiscated from the indivdual nations) to give the impression it is a State in its own right. Meantime, of course, the UK is allowed by the EU to provide its own cash.
However, If there was money coming in (some chance!) it would have to be distributed centrally from the EU. The "poorest" nations would get the lion's share and those well off nations (which, inconceivably considering out current plight, includes the UK) would be at the back of the queue. We would not be allowed to cream off our share first.
The easy answer to this is for governments to cease making these payments, reduce taxation (thus allowing people to keep more of their own money) and let them choose what to spend it on. As has been shown, many of them may wwell spend it on disaster funds. But those who do not feel so inclined would not be forced to do so.