I think you will find that one of their policies was not to renew Trident and invest the billions saved in education,social care and infrastructure, you are right, there is no Fantasy Money Tree ( unless you count Quantative Easing ) but there are plenty of Money Pits.
It's not a surprise they won so many seats when they fought the election on a very anti austerity manifesto. Good for the Jocks, if only we had a mainstream party that came out fighting.