The 28-year-old TV presenter and 27-year-old actress have requested that all their friends attending the wedding - including James 'Arg' Argent, Lydia Bright and Brooke Vincent - at Hengrave Hall in Suffolk bring a glamorous change of clothes for the morning so that everyone will look their best for the magazine coverage they're getting all weekend.
A source said: ''The venue Mark and Michelle have chosen is incredibly posh - it's like somewhere Lady Edith would get married. So guests attending the breakfast the following morning will still have to look swish.
''Obviously, the 'TOWIE' girls have endless wardrobes but some of the other guests are stressing about needing two outfits.They know the wedding party will be full of glamorous people in expensive dresses so it has put the pressure on some non-celeb guests.
''It's all going to be part of the magazine coverage so everyone wants to look their best.''
Speaking to the Mirror newspaper, the source added that some of the guests are even ''planning on getting their hair and make-up done in the morning'' too.
Michelle - whose bridesmaids include Mark's sisters Jess and Natalya Wright - went for her final dress fitting this week, and has previously said she is to wear an ivory dress that she's designed herself on her wedding day.