John, please do a quick search and review the difference.
There's nothing that I can think of that needs to be notarised. That is really verification of signature. Needs a notary public. Expensive.

Certified means to attest that a copy of something is a true copy of the original. Plenty of people are able to do that.

What documents are you thinking need to be:-
a) certified
b) notarised

UKBA need most evidential documents to be originals. Only a few can be certified.

A birth certificate does not need either. For additional true copy just order one.
Just a photocopy of photo page of your passport is ok

Just trying to help.