As you clearly understand, under some circumstances the police must act without prior notification in order to secure evidence, assets, records, etc. However, after the event one would expect a police force in an advanced, civilised country to be open and proper and moreover that a clear, publicly established and fully followed procedure is in place - hoping that it is equitable, thorough and entirely sensible might be too much to ask for in some places. The question is whether this applies in the UK, what type of country it is.
But the other very obvious question is whether you have appointed, or at least consulted, a lawyer - the impression you give is that you have not. It seems to me this would be very unwise, the situation is not going to spuriously disappear and you need to at least get a certain minimum of authoritative advice.