The Gretna area has a surprisingly wide range of shopping to satisfy all requirements, including well-stocked convenience stores, banks, Post Office, chemist etc. to cater for the local population and visitors alike; florists, photographers, hairdessers, dress hire outlets etc.
For anything someone in a wedding party might need or have forgotten; souvenirs, wedding-related items, and traditional Scottish goods for visitors to take home as a memento of their visit; and even Gretna Gatway Outlet Village, offering a wide range of branded clothing. footwear, sportswear, and gift and home items at 30 to 50 % discount all year round.
So, whatever you need, there is a good chance that you will be able to get it while you are here.