The police do have powers of seizure, Cb. Section 19 of the Police and Criminal Evidence Act, 1984 (commonly known as "PACE") says this:
General power of seizure etc.
(1) The powers conferred by subsections (2), (3) and (4) below are exercisable by a constable who is lawfully on any premises.
(2) The constable may seize anything which is on the premises if he has reasonable grounds for believing—
(a) that it has been obtained in consequence of the commission of an offence; and
(b) that it is necessary to seize it in order to prevent it being concealed, lost, damaged, altered or destroyed.
(3) The constable may seize anything which is on the premises if he has reasonable grounds for believing—
(a) that it is evidence in relation to an offence which he is investigating or any other offence; and
(b) that it is necessary to seize it in order to prevent the evidence being concealed, lost, altered or destroyed.
The circumstances you describe almost certainly fit the bill for seizure under S19. I think you have so many problems with this matter that whatever advice you receive on here you will still need legal assistance.