The Hollyoaks actress said that unlike her character Carmel Valentine, she will be leaving the organising to her husband-to-be.
She told Closer: "He's super organised and I'm laid back, so I'll be letting him do the planning. I'd like something small and relaxed."
However, despite being easy-going, the 26-year-old is certain that she wouldn't like a beach wedding.
She added: "My fiancé and I got engaged in the Maldives and wanted a beach wedding, but I hate the heat."
Merna also confirmed that the Hollyoaks cast will be invited to the wedding.