Does dry carbon fibre fabric have a shelf life?

Good news, dry carbon fabric is far more forgiving than prepreg. Because there is no resin in it, there is nothing to advance or cure, so it has no out-life or expiry in the way prepreg does, and a roll kept in good conditions will last a very long time. The things to protect are cleanliness and the surface finish on the fibre, so keep it dry and dust-free, handle it with clean or gloved hands to avoid transferring oils that can affect how well resin bonds later, and store it flat or rolled rather than creased so the fibres are not damaged. Keeping it out of direct sunlight and away from anything that could snag or contaminate it is all it really needs. Stored sensibly, it will be ready whenever the next project is.