1. Assuming you don't have a CSQ, you have to apply to Quebec first. See: http://www.immigration-quebec.gouv.qc.ca/en/index.php
2. When/if you receive a CSQ, you then apply to Sydney NS for the Federal part, and if approved it would be forwarded to London for processing.
Mail your completed application and your fee to the CIO in Sydney, Nova Scotia (Canada):