There are a few sites that i found helpful and informative when looking for, how to gain copies /extracts of wills, etc.

http://www.pro.gov.uk/research/familyhistory.htm

http://www.cyndislist.com

and for those out side of liverpool,and need more recent ,certs,
for birth/death/marriages[ though they might do a two year search, if most info provided, a small fee might be charged.]

Registration of birth,death and marriages,
Cotton exchange
Old hall street
Liverpool 3.
Lancashire.
England.

regards yvonne,