I recently sold my house and had to do the notary thing for the Grant Deed. Good news is that the my escrow rep was very specific about what was required.
Bad news is that no, a UK notary is not enough. Your notary will have to also get you an Apostile.
This is from my escrow company:
"Regarding any notarized documents: our understanding is that it must be a notary with an American consulate or embassy, or the title companies have also stated that the county recorders office is accepting a form of notary called “Apostille” (which is not a document that we generate – the notary would)."
Sadly it still means you need to go to a notary (solicitor) first anyway, pay that fee, and then the solicitor will send off the docs to the foreign office (in Milton Keynes) to get the Apostille cert. It can take up to 4 woking days to be issued. I believe our quote was £85 for the notary, £65 for the courier to Milton Keynes from London, and somewhere around £75 for the Apostile, more expensive for express service!
Maybe check with your county recorders office? It could be different where you are selling.