yes. that is the plan, to have her send them straight after her walk in biometric appointment from a ups or fed ex location by 2 day mail.
What about the rest of her documents? It's not just her passport and the stamped sheet that need to be included from her.
Normally what happens if you send from England is that the US applicant will prepare the entire application, print the application forms (which may need to be taken to biometrics), put all their documents together in the package ready to mail to Sheffield... then instead of it going directly to Sheffield, they send it to their UK spouse, who adds their documents and then forwards the package to Sheffield.
The applicant usually includes:
Basic Documents- Printed online application form
- Completed VAF4a Appendix 2 form
- Stamped Biometrics Confirmation Sheet
- Receipt for IHS surcharge payment
- 2 passport photos
- Her current US passport
- All of her previous passports
- Original divorce decree(s) (if she has been married before)
- Signed cover letter and list of package contents
- Proposed flight itinerary
- Receipt for priority processing
- Return shipping labels
Relationship evidence- boarding passes from trips to see you (if applicable)
- letters/cards you may have sent her since you've been apart
- screenshots of her email inbox showing a selection of dates and subject lines since you've been apart
- screenshots of her Skype/Whatsapp call/message logs showing a selection of dates since you've been apart
- any other relationship evidence she is including... i.e. if you lived together in the US, she will normally be the one including all the evidence of that, since she is in the US - so things like tax returns, house deeds, rental agreements, utility bills covering the time you've been married and living together