How does Courier Services work with Visa Documentation

[iamsuperbritish]

Hello,

I am submitting my wifes visa application and supporting documents to the Sheffield Decision Making centre.

I have all her documents here in the UK and I will be sending it from here via the Post Office.

In regards to them sending it back with all the documents, I do not need to buy their courier service from the VFS Global Website do I?

I can just get a pre paid package with label from UPS or DHL or Post Office addressed to my wife, so they can just put everything in their and send it back to her directly right? (I would overshoot on weight a little and have courier charge me for shipping from Sheffield UK to New York, USA)

Thanks in advance.