The only way, really, would be to put it in the Constitution. Short of that, even if you put it in a bill or a statute, the same government or the next government can repeal the statute, Parliament being sobering. The only way to really make it almost impossible, or difficult, to abolish the program would be to have a constitutional amendment protecting the program. Mind you, doing that could require lots of work; it might not be easy. The constitutional amendment formula would have to be applied. Whether it's to protect the program by putting it in the Constitution, or taking it out of the Constitution in the case where it is in the Constitution, both cases would be difficult to do.
On March 8th, 2016. See this statement in context.