Hi Mac,
Unsure how interflora would introduce this type of product.
The way they work is they promote their brand and take orders then all florist shops across the country who have paid fees to join interflora have to product the order if their shop is the closest to the delivery address.
Obviously, they can not produce personalised roses in each shop across the land without a huge set up cost.
And I think if they said to all their shops / franchises that they are going to produce and sell personalised roses and dispatch from one location, the franchises may be a bit pee'd off. Because thats their income, sales.