A limited company can go bust but the people associated with it would keep their money. They might then make an offer to The Receiver to buy the assets and set up again debt free.
Legally there is no way to keep more than a very small amount for essential living expenses. However we all know of people who have managed to keep £thousands. You just put the cash in someone else account ( as long as you can trust them) or withdraw the cash and hide it somewhere.