I don't believe there's any documentary evidence required by UKBA that needs to be actually notarised.
Occasionally UKBA will state that certified copies of specific documents will be accepted if originals cannot be submitted.
Specifically concerning passport pages many folks just send photocopies and never had a problem.
Some others get the photo page certified. This can be done by a whole range of people much the same as a passport application photo.
Usually original documents are required.