gday luke - for the mould try white vinegar first, or if its bad go the bleach. if its only on the inside you should be fine, outside well you may have to leave it up in the sun a few days with the vinegar treatment. if waterproofing worries you don't be afraid to give it a coat of brellaproof or something - bondrite have a clear one that I use but its hard to get hold of, but generally if it has been seasoned you shouldn't need to worry too much as long as you don't scrub too hard - be prepared to wear out a kitchen sponge or two on it when you give it the vinegar treatment