Labour were not privy to the 22 billion pound black hole during their election campaign. The party in opposition never is. They are always left guessing. The Tories weren't sure of what they were inheriting in 2010 either.
Fixing the NHS? It's a joke. The NHS is a bottomless pit where money is concerned. It's grown too big to be managed because of all the money that's been thrown at it in the past. Giving it even more will make it worse, not better. It needs taking in hand, not drowning with cash.