Morwenna I would not exfoliate the face if you have Rosacea, your skin will easily inflame, so a very gentle approach to skin care is best. A muslin cloth may be a better approach and even that may be too much.
For my face I have a Microfiber Exfoliating Facial Mitt/Cosmetic Glove one side is chamoise the other side is microfiber to exfoliate, its very gentle.
To calm Rosacea a cream called Dermalex Repair skin treatment for Rosacea and Couperose is very good, Boots sell it.