My partner is hiding assets during our separation

The Property (Relationships) Act 1976 contains provisions to deal with this. Both parties must provide full disclosure of their assets and liabilities, and the court can order this. Under section 44 and related provisions, the court can look at dispositions to trusts made to defeat a claim, and can make orders against the trust property or require compensation from other relationship property. A lawyer can seek disclosure of financial records, trust deeds and company accounts, and if required apply for interim orders to prevent assets being transferred. Do not take documents unlawfully; gather what you legitimately have access to, and act promptly.