Caras Regi e Mariana,

o site em inglês (já que vc moraram no UK) sobre as informações oficias similar ao que a Adriana indicou em francês fica em

http://www.cic.gc.ca/english/police-cert/europe/united-kingdom.html

vejam abaixo:

Procedures for Obtaining Police Certificates
United Kingdom (including England, Channel Islands, Isle of Man, Scotland, Wales and Northern Ireland)
Do I need to provide a police certificate when applying for permanent residence?
Yes. Applicants need to provide a Person Record: Prosecution/Criminal History under Section 7 of the Data Protection Act, 1998.

How or where do I obtain one?

Local Requests
Applications (Form 3019A) are available at local police stations. For more information, contact http://www.met.police.uk/dataprotection/faq.htm. To locate local police services, consult the UK Police Web site at http://www.police.uk.

Non-Resident Requests
Applicants may write for the necessary forms and instructions to:

Subject Access Office
Metropolitan Police
10 Broadway
London, England
SW1H 0BG

For Scotland

Data Protection Officer
Strathclyde Police
Police Headquarters
173 Pitt Street
Glasgow, Scotland
G2 4JS

For Northern Ireland
Applicants may request either a “Section 2” search for information from Northern Ireland or a “Section 3” search for a UK-wide search.

Subject Access Office
Criminal Records Office
Police Headquarters
65 Knock Road
Belfast
Northern Ireland BT5 6LE
Telephone: 028-9056-1616
Web site application: http://www.psni.police.uk/dat.pdf

vejam que existem dois sites indicados nesta página oficial do Canadá :

http://www.met.police.uk/dataprotection/faq.htm
http://www.psni.police.uk/dat.pdf

Espero que ajude!

Atenciosamente,

Carlos Luiz