Anyone know what’s happening on Wednesday? Something of a game-changer in the way we live our lives, that’s what. Why, it’s the government’s autumn statement, that’s all.

To all intents and purposes, it’s a budget, a few months ahead of the real budget that comes along in the spring. George Osborne will set out the future of spending for the rest of this parliament. It’s going to be massive. It will define his era as chancellor, it may go so far as to determine the size of the majority the Tories will get in 2020. And it’s going to be horrible.

Work for the public sector? George is going to “trim the fat”, like the 20,000 police officers we no longer need. Well, it’s not as if there’s anything major happening around the world, is there? In fact, there are going to be some 400,000 less public sector workers by 2020, but don’t worry. They’ll only be those who occupy meaningless areas of work, like caring for the disabled, firefighting, coastguards – in fact, the entire public sector with the obvious exception of defence where the country needs as many civil servants as possible.

For a lot of people, the public spending cuts barely register. They read about old people being abandoned to a life of loneliness and despair or a million people relying on food banks or the streets of Bristol seeing, as I saw yesterday, a shocking number of men who looked to all intents and purposes to be homeless (I could not know this for sure but I could think of no other reason why they would lie across the pavements of our city, shivering under crumpled old blankets). Those of us with enough resources to get by outnumbered the poor and abandoned, but they are there all right.

And that’s what worries me about George Osborne’s next round of cuts: they affect the poorest most of all. Public spending cuts always affect the poorest more than the rich. If the rich are taxed a little more, they might have to cut back on the number of holidays they can have. For the poor it is a matter of whether they can eat or whether they have care.

What I see is a broken Britain. It is not the “Broken Britain” David Cameron pretended existed before 2010, but a genuine breakdown in our society. It is the “trickle down” economy which means that as the rich get richer, the lower orders start to benefit too. And it’s an almighty myth.

As Osborne takes the axe to our vital public services this week, we now rely on the opposition to put forward a coherent alternative. Jeremy Corbyn’s uncertain start (to say the least) as Labour leader can be attributed to his inexperience in the higher echelons of politics after a lifetime of speaking to people with whom he agrees. It must be a difficult task to start speaking to those who don’t always agree with him, but this week, he needs to get a grip. We cannot wait for five years to have some alternative to Tory austerity.

We know that Osborne, ever the political tactician, will have at least one rabbit in his hat so Corbyn and his shadow chancellor John McDonnell must expose him for what he is. They need to explain, clearly, concisely and specifically, what Osborne’s cuts will do the country and to the people who live in it, how the cuts will affect the most vulnerable and they will need to set out at least the bare bones of an alternative policy. Talking about an end to austerity in itself is a nice soundbite, but what else and how? And how would this alternative make our lives any better?

We ignore the huge Tory lead in the polls at the moment at our peril. At a time when they are getting the unpopular, nasty stuff out of the way, they are on 42% with Labour down to 27%, the latter a grim reminder of 1983 when Labour plumbed the nadir of unpopularity as Thatcher’s scorched earth politics tore the country apart. Then, a hopelessly divided Labour Party handed the country to her for a generation. Now, it could happen again unless the leadership gets a grip.

As someone who has little time for Corbyn’s far left “new politics”, I am used to and largely immune from the insults and abuse that emanate from the Corbynistas, if you dare to hold a different view. Enough of it has appeared in response to my comments on social networks and it is something which I am well familiar after a lifetime in the Labour Party and the labour movement in general. I bow to no one in my opposition to the Tory party and never will. And that’s why I urge Corbyn, for all his flaws, to get a grip and tear into George Osborne and those who want to turn the public sector into rubble.

A lot is riding on this. Iain Duncan Smith is already soothing the way for the abolition of benefits such as Incapacity Benefits and Unemployment Benefits, turning them into private insurance benefits, and if that succeeds, Jeremy Hunt or his successor will surely do the same with health. Already Osborne is busy flogging off the family silver, selling every asset the public owns to toe sort of people who fund the Tory Party. This is all happening now.

If this is a defining week of this government, then so is it for Corbyn’s Labour. They need to raise their game to a level many of believe is not possible. My dislike of Corbyn’s “new politics” (it isn’t) pales into insignificance compared to what Osborne is about to do but if his election as leader is to mean more than a few handy slogans and vague promises, it is time for him to deliver. For the sake of this country, we must hope he can and does.