How does a bill become a law in the United Kingdom?

If a Bill is passed by the House of Commons, it has to go on to be approved by the House of Lords. Only if it is passed by the Lords can it go on to become law. However, the Commons does have a 'nuclear option' called the Parliament Act, which it can invoke to override the Lords and make the Bill a Law anyway in exceptional or extreme circumstances. However, it is extremely rare for this to be used.