If you purchase a romance package it includes a bottle of champagne waiting in your room upon arrival. If you're not wanting to purchase one we would suggest contacting the resort directly and asking the question.
You will get a glass of champagne upon arrival at the reception area. As as you check in to have room service bring a bottle to your room. They are so fast that i will probably get to the room before you do! We had it delivered every afternoon along with a platter of sweets during the 'Cocktail Hour'.
Go to honeymoon area on the Couple site: http://couples.com/weddings/honeymoonlanding.html, choose a romance package and contact Couples using the "contact us" link on the navbar to set it up in advance. We did last year to celebrate our anniversary and it was great!!
For informational purposes, at the "Renewed Love" (14 to 23 nights stayed) and "Passionate Love" (24+ nights stayed) levels of the Romance Rewards Program, you can get a bottle of sparkling wine as part of your welcome gift. I don't know if this applies to your case, SuzyQ, but it is offered. Another reason to sign up for Romance Rewards. You will want to return again and again.
You can order from room service anytime. They bring champagne to yoru room at no charge - not sure what you mean by a plate of sweets. There are chocolate cake and cheesecake on the room service menu which are available from 11 - 11. Last week we found room service to always be very prompt.