You don't have to be a lawyer to have some understanding of the law. If your wife really did have 30 million in her OWN assets (and not tied up in inheritance etc), and you were living with her and married to her, then that should have been declared and I doubt you would have got unemployment benefits or housing commission housing as she could have supported you. Those benefits are supposed to be only for those who REALLY need them and have no other sources of money. That's what SamanthaJay is getting at, I believe.
And I'm not saying you 'just let it go', I'm saying you'll need to pay for a lawyer to make your claim in the family court. I just don't think it'll be easy and you may expose yourself to having committed fraud in the process.