That’s not how macro works. The UK was never more in debt than just before the Victorian era during which, instead of becoming Weimar Zimbabweslavia, it created the greatest empire the world had ever seen.
It’s not how much in debt you are (well it isn’t if you get to issue your own currency and set your own fiscal policy) it’s what you do with the money. America, likewise, was heavily in debt (and spending vast sums with high taxes) just before it entered its largest period of economic expansion just post WWII.
An important difference is that social programs even if marginally well implemented spread their effects around effectively and boost aggregate demand (which is going to be the bugbear of international macro for the foreseeable future it seems) while bennies for the rich just run through the economy and end up inflating this or that bubble[1].
So, no, the policies listed above will not necessarily tank the economy. They might if managed poorly, but the ones pushed by the Tories are actually far more risky. They burn children hoping to appease the Moloch of austerity and while such stern measures give the appearance of being effective, they, so far, haven’t worked once despite being rammed through in many a poor country by the diktats of the Troika.
[1] 'Cause the poor want money to put their kids through college or to buy a dishwasher and tend to put any windfalls to these economy-boosting purposes. The rich, on the other hand, want somewhere to park their money and so only end up creating a very bullish securities market which bubbles up with leveraged speculator cash until the primary investment stream dries up and then, well. Then 2008.
The Labour party has an image problem. Corbyn, too, in fact. It stems, I think, from an unbalanced target demographic. Labour wants to both provide a robust lefty program for the underclass of Brittain but also to provide the middle class with their conscience-salving indulgences. Empty, meaningless feel-good policies that alienate what should be the party’s base in order to make a certain segment of the chatterati feel okay about making twenty times as the common working class oik.
