Shed Roof Paint/Sealant (Strawberry Hill TW2)

Does any kind person have any leftover paint/sealant that is suitable for use on roofing felt? I only need a small amount (black/charcoal/anthracite colour) as my shed roof is only 4ft x 2ft but it would benefit from a reseal before winter sets in. Any help gratefully appreciated. Kind regards - Cathy.