I have Used many resources when doing my research, many helpful websites are:
Ancestry.co.uk - http://www.ancestry.co.uk/
Ancestry.ca - http://www.ancestry.ca/
Ancestry.com - http://www.ancestry.com/
1911 Census - http://www.1911census.co.uk/
Free Resources
Free Reg is a valuable website, however be aware that many of the records are still being transcribed so if you dont find your ancestor here look in other places - http://www.freereg.org.uk/
Familysearch.org is a reliable source of information - http://www.familysearch.org
Free BMD - http://www.freebmd.org.uk/