No problem!
This is what WES want you to do regarding the degree certificate
“For completed study, you send a clear and legible copy of this document to WES. Do not send your original document.”
The notarization can be made anywhere, just make a copy of your certificate, go to a notary, bring your certificate as well for him to compare the original and the copy you made and he’ll legalize the copy.
About your degree from the UK, I cant say for sure. Just have it assessed from WES first, wait for your results and then when the time comes and you know your results will apply it to your profile. We can only guess what your report might be.
About sending the documents, in general:
If you think its better to send them directly from your university then make the copy of your certificate and give it to your institution to put it in the envelope where the trancripts are.
If you are sending the documents by yourself, make sure to ask your institution to put their stamp, signature and seal it infront of you, you just give them the documents.